The following is an extended English version of the presentation at the Stichting voor de Middeleeuwse Archeologie conference, Dijken, Dammen en Duikers on June 24, 2016. If you would like the Dutch version, contact me. Please acknowledge if citing. – Adam Sundberg

On the 8^th of March in 1732, the Dijkgraaf (Dike Reeve) of Drechterland, Wijnant Nieuwstadt wrote a letter addressed to the University of Leiden. It appealed to the eminent natural philosopher and mathematician Willem Jacob ‘s Gravesande to help with “a terrible judgement from God” that had afflicted West Friesland.[1] This “evil,” he stated, was “ruinous for all of the strongest dikes, piles, and krebbingen” in the region.[2] The cause of his alarm was a “worm” that had “eaten through the piles of several West Frisian dikes, as well as those at Den Helder, Texel, and elsewhere.”[3] This “worm” was in actuality a marine mollusk called Teredo navalis that bored into the wooden components of dikeworks across the maritime provinces.

Shipworms were not new to the Netherlands in the 1730s, but they had never appeared so suddenly and with such destructive consequences. This was the first sustained, explosive outbreak of shipworms in the coastal water defenses of the North Sea. The disaster was an early modern media event that prompted dozens of newspaper articles, pamphlets, and books, not to mention hundreds of governmental decrees and resolutions addressing the subject. It generated international attention from enterprising engineers and scientists wanting to profit from the disaster, just as it prompted self-reflection from moralists criticizing the moral fabric of the Netherlands. Shipworms generated widespread interest, anxiety, even fear among contemporaries. The plague of Teredo navalis, in other words, was a mirror that reflected the cultural and environmental history of West Friesland and the Netherlands.

The shipworm epidemic of the 1730s is not unstudied. It has generated sustained (if relatively minor) interest from scientists and historians since the eighteenth century. Despite its broad significance, however, much of the recent historical research on this period covers its economic and technological consequences. This is perhaps unsurprising. The economic consequences of the outbreak were considerable. Between 1732 and 1743, waterschappen across the Netherlands were forced to expend an estimated 8.1 million florins to rebuild dikes and in in West Friesland alone, the total costs for dike improvements have been estimated at 4.8 million florins.[4] Arriving during an era of secular economic recession in West Friesland and sandwiched in between two deadly epidemics of cattle plague, the economic consequences of shipworm plague were onerous, even disastrous for some communities.

From the perspective of the history of dike technology, shipworms were likewise influential. Dike designs varied, even within a single region like West Friesland, but many employed wooden components, either as wooden palisades or as supporting structures for large, wave breaking cushions. Naturally, shipworm appetites made these designs problematic and water boards across the coastal Netherlands experimented with new dike designs and “remedies” intended to combat this molluscan plague. The extent and speed with which waterschappen implemented these “novel” designs varied, but in West Friesland we can state that the shipworm episode marked a significant breaking point where dike designs increasingly used stone as construction material, either by laying stone in front of the paalwerken and krebbingen (as in parts of West Friesland), or replacing wooden material entirely with gently sloping dikes layered in stone.

In their brief exchange, Nieuwstadt and ‘s Gravesande only implicitly address the pressing economic and technological challenges of the shipworm epidemic, however. Regarding economic concerns, Nieuwstadt merely comments on the impossibility of accounting for the costs of dike repair.[5] When asked for recommendations regarding possible technological remedies for the molluscan infestation, ‘s Gravesande’s replied with caution. He critiqued several possible solutions that had been forwarded to him including the application of a special poison to the wood. “I have no knowledge of anything,” he argued, “that can cleave so tightly to wood that after a few years under water and standing up against the beating of waves with remain.”[6] Despite (or perhaps because of) his experience and reputation, he qualified his input. Although he “examined and sought insight into the subject in a limited capacity,” he replied, “I have to admit that I have little to offer toward the stopping of this evil…I have no research, and I’ve found nothing useful from books on the subject.[7] Instead, ‘s Gravesande commented on the similarities between the “North Sea” worm and other shipworms from the Americas, whether the epidemic would disappear on its own, and the animal’s natural and divine origins.

These were not unrelated considerations to story of dike adaptation in West Friesland and across the Netherlands. In the absence of prior experience with this type of disaster and ready-made solutions, shipworms became useful tools to discuss a wide variety of issues, some of which may seem only tangentially connected to dike repair. Shipworm commentators discussed natural history, the divine origins of natural disasters, creeping environmental changes like the disappearance of voorland, and the economic impacts of other natural disasters like floods and cattle plague. The considerable attention paid to these subjects compensated for a troubling lack of insight into their predicament and, in general, attempted to answer the following questions:

What were the shipworms? Water authorities, natural historians, moralists, and laypeople each grappled with this most fundamental set of questions. Shipworms were not completely unknown to eighteenth century Dutchmen. European mariners, including the Dutch had had a long relationship with shipworms in foreign waters, particularly as their voyages took them into the tropics. There is even some limited evidence of wood borers in Dutch waters as early as the late sixteenth century. Little of this experience translated to a clear picture of habits, life history, or environmental limits of the mollusk. This was an important question, because it explicitly delineated the scope of Dutch vulnerability and the likely duration of the plague.

Prior experience likewise offered only limited insight to a second major question: where did the shipworms come from? Were shipworms indigenous to Dutch waters? Did they simply explode in population because of some environmental influence? Or was it because of Dutch sin and God’s providential wrath? What if shipworms were foreign invaders? Were they unwelcome passengers on East or West Indiamen? This set of questions addressed more than the origins of the disaster, but its ultimate character. They determined whether the epidemic was natural or supernatural; whether this would be the first of several outbreaks; and whether adaptive measures had any chance of success.

Both sets of questions were important because they explicitly framed the disaster as knowable and, therefore, potentially reversible. They laid the groundwork for what political scientist Deborah Stone terms, “causal stories,” or “images” of perception and interpretation that frame disaster response.[8] Simply put, one cannot make changes after a disaster unless one understands what happened. In the context of West Frisian dikes, “causal stories” affected dike adaptation.

These “causal stories” fundamentally grounded a third set of questions: how could the shipworm be stopped? Should solutions focus on killing the mollusks? Should they focus on preventing infestation of the wood? Should the solution be chemical? Mechanical? Spiritual/moral? Should the solution draw upon historic dike designs or depend on innovations? Knowledge of what they shipworms were and where they came from (in other words, the foundations of causal stories), determined which solutions were acceptable.

For the remainder of this talk, I want to outline how these questions were addressed in West Friesland. In doing so, we can develop a clearer picture of why water authorities chose the designs that they did.

What were the shipworms

What were they shipworms? Today, we understand the naval shipworm to be a marine mollusk of the family Terenidae. Shipworms are highly specialized bivalves that consume and live in wood submerged in (to a large extent) coastal areas. They are worm-shaped and have two shells that are used as boring tools. T. navalis is very widely distributed today, from the Sea of Japan to the Swedish coast of the Baltic Sea.[9] This is partly because T. navalis had relatively wide tolerance for environmental conditions. Despite this, temperature and salinity are its two most significant limiting factors.

None of this was known in 1730, however, when the shipworm epidemic began in the Netherlands. First appearing on the island Walcheren in Zeeland during a November storm, the local upper commissioner for the Walcheren water board, Edualdus Reynvaan noted his surprise at this minor storm’s damage: “most of the piles, that otherwise would have been good for years, were not driven out of the ground, but instead were broken above the ground and the reason is that the piles are full of worms.”[10]

Reynvaan was the first to describe the shipworm in detail. He noted that the worms were “2,3,and 4 thumbs in length and a pipe stems thickness entirely of slime foulness.” He went on to note that they were found, not only in the hoofden, but also in the rijsstaken. By the end of the year, Reynvaan discovered that they did not discriminate between oak, birch, willow, or alder and that they infected green and older wood. All of these initial findings would be broadly disseminated across the Netherlands, including to West Friesland, where Nieuwstadt would then forward them to ‘s Gravesande.

The West Frisian theater of the shipworm plague would begin under similar conditions in September of 1731. A wier and palen inspection discovered that strong northern winds and high water had knocked loose several piles along the Drechterlandse Noorderdijk. This was not unusual, however. It was only after rumors of “extraordinary sea worms” in the piles of Texel and Den Helder that the shipworm became a West Frisian disaster.[11] Initial observations of the threat mirrored those in Zeeland. Observers described the worms’ length, their preference for pine wood, and their infestation up to the high tide mark.[12]

It is important to note that these initial observations served as a foundation for later attempts to determine the biology and environmental limits of the shipworm. Many of these early reports were collected in the periodical Europische Mercurius, which published a special “Bericht de plaage der Wormen in the Paalwerk der Dykagien van Holland en Zeeland.” This report drew on the very same dike reports coming out of Zeeland and West Friesland. Knowing what the shipworms were (and were not) was an important precondition to dike repair. This information was doubly important because “strange and outrageous rumors and false descriptions being spread in foreign countries.”[13] One German newspaper reported that Amsterdam’s houses had begun to collapse when their foundations were eaten by worms. Another Swiss newspaper reported that the worms’ heads’ were as hard as iron, they could be two feet long, and the dug holes directly into the dike. Reports like the Europische Mercurius were important because they drew on firsthand observations by dike officials.

Even so, the waterschappen were the first to admit that they needed more information. Even before the publication of the special Mercurius report in August, the “Heeren Dykgraven en Regenten van Drechterland” published a request in the Amsterdamse Courant for anyone who had information or had developed measures against the shipworms to send them to Hoorn and Enkhuizen.[14] In response, Hoorn and Enkhuizen, as well as The Hague, received a flood of suggestions. The earliest reports about what the shipworms were useful because they vetted the most outrageous proposals. Many proposals were rejected because they were unfeasible or too expensive, but many were also rejected because the proposal showed no understanding of the worm itself. Pieter Scheiber of Hamburg’s proposal, for instance, was rejected despite his detailed list of expenditures, because he “Toont groote kennis van geld te hebben, maar geen kennis van de aard der wormen.”[15]

These early questions about what the shipworms were explicitly framed that problem as an engineering problem, albeit one with no clear solutions. Empirical observations confirmed the species was marine (and could not live in fresh water), that it preferred green wood, but would embed itself in almost any native European wood up to the high tide mark, as well as the seasonality of the outbreak. These were important observations because they determined the scale of vulnerability of West Frisian dikes. Following the 1731 inspection of the Vier Noorder Koggen dikes, the only areas that were not infected were those that dried on a daily basis.[16] These reports also gave observers no reason to believe the shipworm infestation would end on its own. In his reply to Nieuwstadt, ‘s Gravesande noted with “groot leet,” “dat ik geloven weeten dat men sigh sonder rede vleyt dat dese plaag zal komen te cesseeren…het is wel apparent dat de schade onvergelykelyk grooter zal syn als tot noch toe is begroot.”[17] A remedy needed to be found, but what kind would be effective?

Where did the shipworms come from?

The initial response to shipworms was the search for a mechanical remedy, but by 1732 the realm of available solutions had widened considerably. This was largely due to the widespread popular response to the call for solutions. Remedies, however, came in many different forms. Poisons, smeersels, iron buttresses, and new designs for dikes arrived from across Europe. As news of the disaster spread, spiritual solutions became more popular. Finally, the shipworm epidemic sparked a minor outpouring of scientific literature on the subject. Between 1732 and 1735, the shipworm epidemic became a truly public, national disaster. In addition to describing the shipworms, these popular discourses addressed a second critical question: where did the shipworms come from? The question of the shipworms’ origins was a necessary component of a causal story.

From the perspective of modern scientists, shipworms are still somewhat a mystery. They are considered a “cryptogenic species”; they have no known origin.[18] The earliest accounts of shipworms in European waters date to the 4^th century B.C., though it is impossible to determine whether this was T. navalis.[19] Dutch mariners certainly came into contact with shipworms on a consistent basis after the expansion of Dutch trade into the tropics in the late 16^th and 17^th centuries. Dutch shipbuilders already considered T. navalis the principle hazard of tropical commerce by the early 17^th century. Almost every VOC ship bound for Asia had shipworm “verdubbelen” – a triple layer of oaken hull, a layer of lead or hair nailed to the oak, and a soft pine wood over that.[20]

Shipworms may have even arrived in the Netherlands prior to 1730. Reports noted damage possibly resulting from shipworms in Dutch waters as early as the 1580s. However, this damage was either limited to marine vessels or the damage cannot be conclusively linked to T. navalis.[21] Contemporaries to the shipworm epidemic could likewise find no agreement as to the origins or duration of the shipworms presence. Adriaan Bommenee, hoofd van openbare werken in Verre, noted in retrospect that the shipworm had been known to everyone “in memoriale tyden,” but they had always existed in limited numbers.[22] On Walcheren, Edualdus Reynvaan argued that “Ik en hebbe in myn tyd van 30 Jaren, dat aan de Dyk hebbe verkeert noit een worm ondekt; oude arbeiders van 80 Jaren verklaren ook noit ondervonden te hebben. Ik en vinde ook in geen Notulen van het Jaar 1550 af dat er mentie van sulken quaad wort gemelt…”[23]

The shipworm epidemic also catalyzed intense scientific interest. Between 1733-35, a number of Dutch and international scholars contributed their insights into the origin and biology of the shipworms. Many recognized that this was a prime opportunity to produce meaningful, very public work. Jean Rousset de Missy, for instance, noted that “The Damage, which hath been caus’d by certain Sea – Worms, to the Pile-Works of the Dykes of Zealand, North -Holland Friesland, and the Coast of Flanders, hath made so much Noise, that it is no Wonder the Curiosity of the Publick, and particularly of Gentlemen who employ themselves in the Study of Natural Philosophy, hath been awaken’d to look narrowly into this Phenomenon.”[24] Perhaps the most famous contribution came from the Prussian natural historian Gottfried Sellius, whose observations would later serve as the basis for Linnaeus’ taxonomy of the species. Although much information was shared (or copied) between the authors, their conclusions could be widely varied. In his 1735 treatise on the shipworm, Abraham de Bruyn, listed eight different theories as to the origin of the shipworm, from “they came from the east or west indies,” “they came from heat and siltiness of the North Sea,” to “they developed out of oyster banks.”[25] Authors differed in their conclusions about the role of sea temperature, salinity, and the means of reproduction. What De Bruyn, Belkmeer, Bommenee, and Reynvaan could agree on (and this was broadly felt in West-Friesland after 1731 as well), was that the ultimate origin of the shipworm plague was God.

By far the most common explanation for the arrival of the shipworms was God. Shipworms were a judgment from God for the sinful state of the Netherlands. It is easy to dismiss this discourse as formulaic. Divine judgment, after all, was not an explanation for disasters specific to the eighteenth century. Several conditions about the shipworm epidemic appealed more strongly than to the role of God other disasters. First, it’s timing could not have been less ideal. By the early eighteenth century, much of the coastal Netherlands was undergoing a secular economic recession. West Friesland was particularly hard hit. A number of provinicial governments, as well as the Staten Generaal declared “Dank, Vast, and Bededagen” to ask God to end this era of disaster. The Staten van Holland en Westvriesland, for instance, called on all of the United Provinces to observe a day of repentance on the 11 of May, 1733 because of the “vermindering van Navigatie en Commercie, door swaare Waatervloeden, door ongemeene siektends en starfte onder Menschen en Rundvee, en nu laatstelijk door een ongewoone plaage van schaadelijk Gewormte in Paalen en Houtwerken.”[26] Only a decade earlier, the first of three epidemics of cattle plague (likely rinderpest) had swept across the Netherlands, decimating herds and memories of previous disasters, including the flood 1675 had not yet faded. In this climate of dearth and disaster, the shipworms arrival signaled a renewal of hard times and further confirmation of God’s role.

It is likewise easy to dismiss this discourse as the superstitious paranoia of early modern societies. The shipworm was strange, however. Common on voyages to the tropics, shipworms were largely unknown in the Netherlands. The scale and severity of the 1730 outbreak was absolutely unheard of. With no prior experience and no proven explanation of natural origin, divine explanations were a logical conclusion.

As part of a “causal story,” divine judgment could work with naturalistic explanations or against them. For instance, although Reynvaan, Bommenee, and De Bruyn all subscribed to naturalistic explanations for the sudden appearance of the shipworms (mostly due to climate changes), all attributed the shipworms ultimately to God. As a causal element of the shipworm epidemic, God’s role did not preclude material changes to dikes. Naturally, an exclusive form of providentialism would not fit the causal stories of dike officials like Reynvaan or Bommenee or wetenschappers advertising remedies for the shipworm epidemic like De Bruyn.

Many commentators during the eighteenth century had less interest in dike repair, however. Dutch morality in their view also required saving. A wave of providentialist books and pamphlets appeared between 1732 and 1735 warning of “Gods slaande hand over Nederland.” The shipworms, according to many pamphlets, were more than a sign of God’s displeasure; they were a sign of more terrible disasters in the future. Friesland’s 1732 plakkat for a Dank, Vast, en Bededag echoed much of the early confusion and frustrations of the waterschappen. The shipworms, it stated, are “Voorwaar een vreeslyk Oordeel Gods alhier nooyt bespeurt, waar af de oorspronk nog de voorteelinge, de kragt nog de sterkte tot nog toe door geen Menschelyk vernuft of schranderheyd kan gepeylt of nagespeurt werden, veel min eenige Remedie uytgevonden om de Goddelyke Plage af te wenden.”[27] In this causal story, the fact that shipworms evade explanation and remedy is justification of their divine origins and a divine solution.

Between 1732 and 1735, Dutch commentary on shipworms dramatically expanded. Water management officials remained actively involved, but new participants like natuurwetenschappers, moralists, and the broader public offered different interpretations of what the shipworms were and where they came from. These interpretations formed the basis for “causal stories” that turned a confusing, dangerous situation, into a problem that could be solved.

How could the shipworms be stopped?

Water boards’ primary challenge in the initial period of the outbreak had been its novelty. By 1733, new information and an expanded public discourse created a number of different options for dike authorities tasked with rebuilding West Frisian dikes. Moralists who held exclusive providentialist views, presented spiritual solutions like public prayers, penitence, and remembrance. Wetenschappers offered solutions that drew on their empirical observations of the biology and ecology of the mollusk. The wealth of proposals sent to West Friesland and The Hague at the request of the waterschappen tended to favor innovative and (supposedly) exclusive remedies. The waterschappen were publically open to new designs and conducted extensive tests of many. Causal stories framed each of these realms of action. In the end, they favored a capital-intensive solution based on established dike designs. This solution adhered to a causal story grounded in new knowledge of shipworms, but one that ultimately turned shipworms into flood risks.

The response from waterschappen began immediately, but reports were often couched in tentative language. A letter from Edualdus Reynvaan, for instance, noted that “little can be said with certainty” about how to remove the mollusks.[28] In general, waterschapsbestuur remedies can be roughly divided into two realms: 1. Rebuilding dikes with little alteration 2. Relying on maritime experience with the shipworms. The initial response was simply to repair with some minor alterations. Later, inspectors from a commission established by the Staten van Holland presented a “nieuw manier van dijkagie” whereby the krebbingen that had held the wier in place would be removed. Instead, piles would be perpendicularly driven through the wier to fasten it to the sea floor.[29] This method proved both expensive and susceptible to damage by waves.[30]

At the same time, the Holland commission was testing a variety of proposals from near and far. Many remedies drew, to a large extent, on the measures taken to protect ships. Reynvaan noted their experiments with the piles. They burned the outside of the piles, coated them with tar, harpuis, and hair, and noted their effectiveness. They also noted their unworkable costs. Maritime experience with shipworms was useful, it seems, but it was not workable on the scale of Dutch coastal defenses. In response, they turned to outside information. Indeed, the vast majority of solutions available to the waterschappen of West Friesland came from outside their institutional organizations. Suggestions came from as far afield as Switzerland, France, and Italy. Many of these remedies were tested in West Friesland and the majority were variations on the maritime solutions tested in 1732. One of the more interesting solutions drew on a different maritime strategy to protect ships, this time by cladding the outside of dikes in large, flat copper wormspijkers. Records from England date this technique with lead to as early as the 17^th century, and possibly as early as the ancient Phoenicians.[31] Versions of this remedy were tested in Zeeland and West Friesland. In Drechterland in 1733, test piles with copper cladding were found to be the only piles that were not infected, but because of their great expense, “no award for this test can be given.”[32] While this method was too expensive to be employed on every dike, they were used to protect areas with little to no land in front of dikes, such as harbors or sluices.[33] In sum, the initial response on the part of waterschappen was to focus on the mollusks themselves. From the perspective of causation, animals were the source of their problems. Their solutions focused on those animals and drew on centuries of received wisdom from mariners. Dikes were not ships, however. Years of testing based on maritime knowledge of the worms reinforced the effectiveness of their methods, but proved impossible to employ on such as large scale. A different solution was needed.

A second set of solutions came from wetenschappers. They saw the vacuum of information available to waterschappen as an opportunity. Cornelis Belkmeer addressed his treatise to the commission established by the Staten van Holland to inspect the West Frisian dikes. Indeed, the majority of the natural historical treatises produced about shipworms between 1733-1735 self-consciously advertised the practical benefits of the “new” knowledge they produced. Unlike other participants, these authors tended to promote solutions that drew on their new findings. For instance, a source of debate amongst authors was the reproduction of shipworms. Many authors observed a white slime on the outside of the piles and concluded it contained shipworm eggs. As a result, Belkmeer suggested burning the outsides of the piles to harden them and then scraping the slime with “yzere schrapers en styve borstels.”[34] Although none of their solutions were accepted, a few were considered. The commission for the repair of the West Frisian sea dikes estimated the cost of Rousset’s remedy at 1.36 million guilders, but left no record of its success or failure.[35] Like the early proposals and experiments conducted by the waterschappen, the wetenschappers largely interpreted the cause of the disaster to the shipworms themselves. Unlike the waterschappen, however, they typically sought a deeper level of causation. They sought new information about the biology and origins of the shipworm that might offer insight to potential remedies.

A third set of potential solutions was spiritual. Dank, vast, and bededagen were the core remedies, though many providential texts also recommended more comprehensive individual spiritual renewal as well. According to the “sin economy” of divine providence, Dutch sin directly translated to natural disasters. This causal framework made little distinction between “kinds” of natural disasters. Veepest, overstromingen, fires, and shipworms all required the same solution. In fact, the strangeness and unprecedented nature of the shipworm threat was ideally suited to providentialist interpretation. Providential remedies were likewise flexible. While a few exceptional moralists fatalistically warned that attempting to remove the shipworms would only bring more terrible punishments, most easily mingled with secular solutions.[36] Indeed, the success or inventiveness of remedies against the shipworms was also often attributed to God. Henricus Engelhardt, for instance, attributed his “goede sufficante middellen” to his “groote zorgvuldigheid en smekinge tot God.”[37] Providential remedies were not insignificant. Unlike many of secular plans or remedies, spiritual solutions were invested with institutional authority from both church and state. The concurrent performance of spiritual and secular remedies speaks to confidence in both.

A final set of potential solutions developed out of the exhaustion of other options. Although some had proved feasible, none fit the requirements of being impervious to shipworms, durable against the sea, and cost effective. The solution in West Friesland developed out of a reassessment of the nature of the disaster. Why was Pieter Straat and Pieter van der Deure’s design so successful? Naturally, it helped that both were waterbestuurders in West Friesland. They promoted the innovative qualities of their designs. They called their proposal a “nieuwe manier van Dykagie” never before used, which “Kayen en Klipsteenen aan den Dyk te doen brengen, en dezelve Glooiewyze van de Dyk af Zeewaart in te leggen, het welk een onfeilbaar middel zoude zyn omme de Dyken tegen het woeden der Zee te beveiligen.”[38] This is perhaps an overstatement. The use of stone on the seaward slopes of dikes date back to at least the 16^th century from the journals of Adries Verlingh. Straat and van der Deure’s designs could likewise be considered modifications to existing dikes rather than a completely new design. Rather than removing the wier and palen completely, stone was gradually used to cover the outermost slopes of the most threatened dikes.

More than than that, Straat and Van der Deure proposed a solution that drew on multiple levels of causation. It drew on providential (even existential) language, crediting God for their inventiveness and calling on God to protect the Netherlands. To a certain extent, they acknowledged the causal significance of the shipworm animals. Their design worked because shipworms could not infest wooden components hidden under layers of stone.

Perhaps more important was the degree to which their design removed shipworms from the equation. Shipworms are almost an afterthought in their proposal. The same animals whose mysterious origins, spread, and existence had proved so problematic for waterbestuurders and terrifying for the broader public were largely ignored. Straat and van der Deure were successful because they shifted the causal story to familiar territory: flood vulnerability. Their designs would be beneficial regardless of the shipworms. Even if the “zeeworm geheel en al ophield, en nooit weder te voorschyn kwam,” they argued, the dikes would be left stronger and cheaper to maintain in the long term.[39] The “grootste bekommering ontstaat in stormen en tempeesten, dat men niet kan ontdekken noch verzekert zyn.”[40] They also advertised the proposal as a measure to prevent the loss of coastline, an ever present issue that had necessitated the creation of wierdijken in the first place. Shipworms had already catalyzed widespread public participation in water management, dike design, and the natural history of the mollusk. They inspired numerous designs, patents, and books promoting remedies and new ideas about the cause and solution to the epidemic. In the end, it was only when shipworms had been converted back to the familiar threat of inundation that a suitable remedy was accepted.

[1] By the mid-18^th century, authorities like Nieuwstadt were increasingly calling on university faculty to consult on challenging water management dilemmas and this was not ‘s Gravesande’s first request. ‘S Gravesande was part of an increasingly influential circle of scientists at the University of Leiden (including Hermann van Boerhaave) that trained a new generation of hydro engineers and surveyors, many of whom were employed in Rijnland. Zeischka, Siger. Minerva in de polder: waterstaat en techniek in het hoogheemraadschap van Rijnland (1500-1856). Uitgeverij Verloren, 2007., 288.

[2] “een zwaar ordeel van godt…ruineus voor alle zwaarte dycken, met palen krebbingen” Nieuwstadt, Wijnant. “Brief van W. v[an ?] Nieuwstadt aan Willem Jacob ’s Gravesande (1688-1742) over het voorkomen van de paalworm in Noord-Holland. 8 Maart 1732. Met kopie van een brief uit Middelburg daarover, 9 Februari 1732 en de minuut van het antwoord van ’s-Gravesande.” Koninklijke Bibliotheek, n.d.

[3] “gewurmten, waar door de palen aen de westvriesse dycken, in aen den Helder, Texel, in elders meer werden doorgegeten” Nieuwstadt, Wijnant. “Brief van W. v[an ?] Nieuwstadt aan Willem Jacob ’s Gravesande (1688-1742) over het voorkomen van de paalworm in Noord-Holland. 8 Maart 1732. Met kopie van een brief uit Middelburg daarover, 9 Februari 1732 en de minuut van het antwoord van ’s-Gravesande.” Koninklijke Bibliotheek, n.d.

[4] Baars calculates a total cost in Holland of 6.5 million florins between 1732-1743/ Baars, C. “Nabeschouwing over de Paalwormplaag van 1731-32 En de Gevolgen Daarvan.” Waterschapsbelangen 75 (1990): 507.

[5] Nieuwstadt, Wijnant. “Brief van W. v[an ?] Nieuwstadt aan Willem Jacob ’s Gravesande (1688-1742) over het voorkomen van de paalworm in Noord-Holland. 8 Maart 1732. Met kopie van een brief uit Middelburg daarover, 9 Februari 1732 en de minuut van het antwoord van ’s-Gravesande.” Koninklijke Bibliotheek, n.d. “waar tegens men de kosten niet kan computeeren”

[6] “Ik hebben geen denckbeelt van ietswas dat soo vast aan het hout soude kleeven, dat het eenige jaaren onder water daar op soude blyven, en het slaan van de zee tegen staen.” Nieuwstadt, Wijnant. “Brief van W. v[an ?] Nieuwstadt aan Willem Jacob ’s Gravesande (1688-1742) over het voorkomen van de paalworm in Noord-Holland. 8 Maart 1732. Met kopie van een brief uit Middelburg daarover, 9 Februari 1732 en de minuut van het antwoord van ’s-Gravesande.” Koninklijke Bibliotheek, n.d.

[7] “saak naar mijne geringe capaciteeyt geexamineert, en overal licht gezocht, doch weynig occasie daar toe gevonden buyten de papieren bij UW Edele missive ge[rigten] en ik moet tot mijn [leeswesen seggen dat ik wijnig hebbe in te brengen tot sluyting van het kwaad, daar het nochtans aankomt, ik heb geen ondervinding relatief tot dese saak, en niets inde boeken gevonden dat mij inde dese kand te hulp komen.” Brief van W. v[an ?] Nieuwstadt aan Willem Jacob ‘s Gravesande (1688-1742) over het voorkomen van de paalworm in Noord-Holland. 8 Maart 1732. Met kopie van een brief uit Middelburg daarover, 9 Februari 1732 en de minuut van het antwoord van ’s-Gravesande.

[8] Stone, Deborah A. “Causal Stories and the Formation of Policy Agendas.” Political Science Quarterly 104, no. 2 (1989): 281–300.

[9] Kulikova, V. A., N. K. Kolotukhina, and V. A. Omelyanenko. “Pelagic Larvae of Bivalve Mollusks of Amursky Bay, Sea of Japan.” Russian Journal of Marine Biology 40, no. 5 (2014): 333–43; Appelqvist, Christin, Jon N. Havenhand, and Gunilla B. Toth. “Distribution and Abundance of Teredinid Recruits along the Swedish Coast – Are Shipworms Invading the Baltic Sea?” Journal of the Marine Biological Association of the United Kingdom 95, no. 04 (June 2015): 783–90.

[10] “meest al de Paalen niet zyn uyt de grondt maar gelycks en boven de grondt zyn Afgebrooken die anders Nogh meenige Jaaren Zoude goet zyn geweest zyn de Reeden is dat al de Paalen vol wormen zyn.” “Notulen van de Staten (en Gecommitteerden van de Breede Geërfden), 1511-1812.,” November 23, 1730. 3000.20. Zeeuws Archief.

[11] Geschiedenis der stad Hoorn, hoofdstad van West-Vriesland, gedurende het grootste gedeelte der XVII en XVIII eeuw, of vervolg op Velius Chronyk: Voortgezet tot op het jaar 1773. bij Gebr. Vermande, 1842., 243-44.

[12] anon. “Beschryvinge, van de Schade En Raseringe Aan de Zee-Dyken van Noort-Hollanden West-Vriesland, Door de Worm in de Palen, En de Daar Op Gevolgde Storm, En Vervolgens: Waar by Komt Een Beschryving van Een Nieuwe Water-Machine.” Hoorn, 1732.

[13] “Vervolg van Het Bericht Wegens de Plaage Der Wormen in Het Paalwerk Der Dykagien van Holland, Enz. Mitsgaders van Middelen Tot Stuiting van Dat Kwaad En Tot Verandering En Verbetering Der Dyken Voorgeslagen: Als Mede de Ontdekking van Dat Kwaad Op Andere Kusten.” Europische Mercurius 43.2, 307.

[14] Amsterdamse Courant, July 5, 1732.

[15] Gedeputeerden van Haarlem ter Dagvaart. Nationaal Archief. 3.01.09 1238.

[16] Baars, C. “De Paalwormfurie van 1731-1732 En de Schade Aan de West-Fries Zeedijk.” Waterschapsbelangen 73 (1988), 813.

[17] Nieuwstadt, Wijnant. “Brief van W. v[an ?] Nieuwstadt aan Willem Jacob ’s Gravesande (1688-1742) over het voorkomen van de paalworm in Noord-Holland. 8 Maart 1732. Met kopie van een brief uit Middelburg daarover, 9 Februari 1732 en de minuut van het antwoord van ’s-Gravesande.” Koninklijke Bibliotheek.

[18] Hoppe, K.N. “Teredo Navalis – The Cryptogenic Shipworm.” Invasive Aquatic Species of Europe; Distribution, Impacts, and Management, 2002, 116–19.

[19] Steinmayer, Alwin G., and Jean MacIntosh Turfa. “Effects of Shipworm on the Performance of Ancient Mediterranean Warships.” International Journal of Nautical Archaeology 25, no. 2 (May 1, 1996): 104–21.

[20] Parthesius, Robert. Dutch Ships in Tropical Waters : The Development of the Dutch East India Company (VOC) Shipping Network in Asia 1595-1660. Amsterdamse Gouden Eeuw Reeks. Amsterdam: Amsterdam University Press, 2010, 102-103.

[21] Wolff, Wim J. “Non-Indigenous Marine and Estuarine Species in The Netherlands.” Zool. Med. Leiden 9 (2005), 86.

[22] “Testament van Bommenee’, Register Houdende Bouw- En Waterbouwkundige Aantekeningen van Diverse Aard, Samengesteld Door Adriaan Bommenee,” n.d. Verzameling Handschriften Gemeentearchief Veere. Zeeuws Archief., 206. [23] Reynvaan, Edualdus. “Missive Uit Zeeland over ’T Grasseeren Der Zeewormen Aldaar,” February 9, 1732. Ambacht van West-Friesland genaamd Drechterland en hoofdingelanden van West-Friesland. Westfries Archief.

[24] de Missy, Jean Rousset. Observations on the Sea- Or Pile-Worms Which Have Been Lately Discover’d to Have Made Great Ravages in the Pile-or Wood-Works on the Coast of Holland, &c: Containing A Particular Account of Their Make and Nature, and of the Use of Their Several Parts in Boreing and Feeding; with a Particular Description of Their Cells Or Lodgments in the Wood. London: J. Roberts, 1733.

[25] Abraham de Bruyn, Den Zeeworm beschouwd in zyn eigen aard en natuur … Mitsgaders een overweginge hoe, en wat voor middelen met vrugt en voordeel tegens dit verderf, en den zeeworm konden gebruikt worden, 1735, 52-62.

[26] “Plakkat (17 Feb),” 1733. Archief van de Burgemeesters. Stadsarchief Amsterdam.

[27] van Wyckel, J.S. “Placcaat. Uitschryving van Den Algemeenen Dank- Vast- En Beeden-Dag, Gehouden Binnen […] Vriesland, Op Woensdag Den 3. September 1732.” ’s Granvenhage, 1732, 5.

[28] Reynvaan, Edualdus. “Missive Uit Zeeland over ’T Grasseeren Der Zeewormen Aldaar,” February 9, 1732. Ambacht van West-Friesland genaamd Drechterland en hoofdingelanden van West-Friesland. Westfries Archief.

[29] Baars, C. “Nabeschouwing over de Paalwormplaag van 1731-32 En de Gevolgen Daarvan.” Waterschapsbelangen 75 (1990): 504; “Voorslaagen En Calculatien, Dienende Tot Een Plan, Hoedanig En Op Welke Manieren de Door Wormen Beschaadigde Zeedijken van Dregterland, Vier Noorder Coggen, Geestmer Ambagt, Schaager En Niedorper Coggen, Het Best Te Repareeren En Te Onderhouden Soude Zijn Tegen Het Geweld En Doorbraake Der Zee,” May 29, 1732. Archief van de Burgemeesters-Resoluties van de Staten van Holland. Stadsarchief Amsterdam.

[30] Baars, C. “Nabeschouwing over de Paalwormplaag van 1731-32 En de Gevolgen Daarvan.” Waterschapsbelangen 75 (1990), 504.

[31] Carlton, J. T., and J. Hodder. “Biogeography and Dispersal of Coastal Marine Organisms: Experimental Studies on a Replica of a 16th-Century Sailing Vessel.” Marine Biology 121, no. 4 (February 1995), 721-730; Woods Hole Oceanographic Institute. “The History of the Prevention of Fouling.” In Marine Fouling and Its Prevention. Annapolis, Maryland: United States Naval Institute, 1952.

[32] “Letter from Seger Lakenman to Monsr. Boekholt,” n.d. Slaan van proefpalen en beschouwingen van E. Reynvaan te Middelburg, J.H. Eekholt te Groningen en J. Bushell over het optreden van de paalworm en manieren om hout tegen deze worm te beschermen, 1732-1734 en z.d. Westfries Archief.

[33] Bartels, Michiel H., Peter Swart, and H. de Weerd. “Wormspijkers in het Medemblikker havenhoofd Archeologisch en historisch onderzoek naar de maatregelen tegen de paalworm in het noordelijk havenhoofd van Medemblik, West-Friesland, NL.” West-Friese Archaeologische Rapporten 80 (2015).

[34] Belkmeer, Cornelis. “Naturkundige Verhandeling of Waarneminge, Betreffende Den Hout-Uytraspende En Doorbooren de Zee-Worm.” Amsterdam, 1733, 44.

[35] 28 Mar., 1733. Gedeputeerden van Haarlem ter Dagvaart. Nationaal Archief. 3.01.09 1238.

[36] Mobachius, Johannes A. De Almagtige En Regtveerdige Slaande Hand Gods, Ter Besoeking van Het Land En Deese Provincie Met de Verderfelyke Plage Der Zeewormen, Vertoond En Aangedrongen Uit Nahum I: Vs. 3; Op Den Plegtelyken Vast-En Bid-Dag, Gehouden in de Provincie van Groningen Ende Ommelanden, Den 8 Octob. 1732 …; Al Waar Met Een Ingevoegt Is Een Beschrijving van de Gedaante En Grootte Der Zeewormen, En Hoe Die de Dijkpalen Doorboren Nevens Een Afbeelding Daarvan. Groningen: Jurjen Spandaw, 1733, 49.

[37] Engelhardt, Henricus. “Goede Suffisante, Gods Verleende, Uitgevondene Middelen, Omme Yzere, En Steene Zeemuuren, Met Paalen Zonder Metzelwerk, Tegens Het Schadelyke Zeegewormte Te Maken, Dewelke in Plaats van Zeedyken, Dammen, En in de Zehavens Zoude Kunnen Dienen.” ’s Gravenhage, 1733, 3.

[38] Straat, P., and van der Deure. “Ontwerp Tot Een Minst Kostbaare Zeekerste En Schielykste Herstelling van de Zorgelyke Toestand Der Westfriesche Zeedyken… Met Een Nader Ontwerp Hoe Men de Dyken Daar de Grootste Dieptens Zyn Op de Zekerste, Minst Kostbaarste En Schielykste Wyze Kan Herstellen… Door Pieter Straat En Pieter Van Der Deure.” Amsterdam, 1733, 6.

[39] Straat, P., and van der Deure. “Ontwerp Tot Een Minst Kostbaare Zeekerste En Schielykste Herstelling van de Zorgelyke Toestand Der Westfriesche Zeedyken… Met Een Nader Ontwerp Hoe Men de Dyken Daar de Grootste Dieptens Zyn Op de Zekerste, Minst Kostbaarste En Schielykste Wyze Kan Herstellen… Door Pieter Straat En Pieter Van Der Deure.” Amsterdam, 1733, 19.

[40] Straat, P., and van der Deure. “Ontwerp Tot Een Minst Kostbaare Zeekerste En Schielykste Herstelling van de Zorgelyke Toestand Der Westfriesche Zeedyken… Met Een Nader Ontwerp Hoe Men de Dyken Daar de Grootste Dieptens Zyn Op de Zekerste, Minst Kostbaarste En Schielykste Wyze Kan Herstellen… Door Pieter Straat En Pieter Van Der Deure.” Amsterdam, 1733, 23.

Dikes, dams, and culverts. These were the themes of the recent conference sponsored by the Stichting voor de Middeleeuwse Archeologie (Association for Medieval Archaeology). The organizers laid out a short, one-day conference featuring recent archeological, historical, and geographic research on the subject of water management and water defense. Papers spanned a broad period of time, from Roman era dikes in Zeeland to ongoing efforts by the Rijksdienst voor Culturele Erfgoed (Institute for Cultural Heritage) to manage and protect dikes today and in the future.

The Oosterkerk in Hoorn prepares for a day-long conference on Dutch dike history and archeology.

Hosted by Archeologie West-Friesland and MC-ed by the inimitable Michiel Bartels, the conference took place in the port town of Hoorn in Northern Holland. A former trade headquarters for the VOC (Dutch East India Trading Company), the city boasts a fantastic history and a well-preserved city center that hugs the west coast of the former Zuiderzee. Unlike many similar-sized cities in the Netherlands, Hoorn’s former wealth (generated during the 17^th century Golden Age) remains on full display. The conference location, the impressive Oosterkerk, is evidence of this past.

Hoorn during its ascendancy.

The conference itself showcased recent scholarship conducted on Dutch (and northern German) dikes. It also served as a sort of context for the publication of a new multi-volume book called Dwars door de Dijken (“Straight through the Dikes”). This book is a comprehensive account of recent research into West Frisian dikes and dike ecosystems (including both environmental ecosystems as well as the structures and landscape features that typically accompany coastal dikes such as sluices, dijkmagazijnen, voorland, etc.). The book is an impressive interdisciplinary collection that documents over half a decade of research made possible through the cooperation of numerous parties, including the Stichting voor the Middeleeuwse Archeologie, Hoogheemraadschap Noorderkwartier, Stichting Archeologie West Friesland, and the municipality of Hoorn.

The conference featured a wide variety of disciplines and specializations. Petra van Dam kicked off the event with a thoughtful consideration of the role of dikes and other adaptive measures that tended to limit flood fatalities in the middle ages. Working on themes framed by her work on the amfibische cultuur, Van Dam noted the importance of early warning systems, fleeing to high ground, and compartmentalization of the landscape to slow the advance of inundation. These cultural adaptations to flooding were key strategies, Van Dam maintained, that medieval inhabitants of coastal regions and floodplains used to mitigate disaster.

One of the most compelling presentations was by Seger van der Brink. A geologist and maritime archeologist, Van der Brink presented the fascinating case of the “verdronken dijk van Texel.” Using sidescan sonar, an acoustic technique of visualizing the sea bottom, Van der Brink and his team discovered the remains of what appeared to be large rectilinear form under the Marsdiep approximately 600 meters from the shore of the North Holland island Texel.

The “drowned dike of Texel” Kaart van het Horntje, Mattijs den Berger, 1751: http://tresor.tudelft.nl/kaarten/webpages/TRL_12_1_2_17.html

Van der Brink presented this case almost as if it were a detective story, beginning with the accidental discovery of the anomaly, followed by historical cartographic evidence (sadly no documentary evidence), finally revealing its identity as a dike constructed in 1749 and reinforced with stone (likely a result of the “petrification” of the Zuiderzee coastline due to the shipworm). The dike disappeared in 1792 as a result of the changing dynamics of the Marsdiep, though sadly, the story of the dike’s disappearance was not a central element of the talk. Nevertheless, the dike is the largest underwater find in the Netherlands and was an impressive showcase of recent work in maritime archeology.

Luuk Koenen, from the independent archaeological firm RAAP spoke about recent excavations of a dike along the Waal River to the north of Nijmegen. Aside from research into the structure of the river dike, RAAP is also conducting historical-geographic information about landscape use and landownership using documentary data. Sander Gerritsen presented a very animated and enjoyable talk about Archeology West Friesland’s excavation of the Klamdijk (the same dike I visited last year) and Robert van Dierendonck presented findings on three different ancient and medieval dikes in Zeeland.

The keynote address was shared by three German archaeologists: Sonja König from the Ostfriesische Landschaft Archäologischer Dienst and Anette Siegmüller and Johannes Ey from the Niedersächsischen Instituts für historische Küstenforschung. Their presentation reconstructed the dike profile of a paaldijk near the Eems river close to the border of the Netherlands in the Dollard region. I had known that German and Dutch dikes often shared certain characteristics. Dikes are like extended families. Close relationships seem to follow geographic proximity, but (because of information networks) dikes in regions far from one another remain “cousins,” sharing notable features. Paaldijken are a case in point. Some coastal dikes in the Dollard region in German used long palisade-style wooden constructions to protect the earthen portion of the dikes from the force of waves. These were likewise employed in Friesland and the Zuiderzee region (now the IJsselmeer).   König, Siegmüller, and Ey’s presentation laid out the historical development of this dike from a minor embankment to the modern construction one can visit today.

Two points were of particular consequence for me: first, that this paaldijk was not infected by shipworms. This is to be expected in an area bordering the Eems. Shipworms avoid areas with low salinity like the mouths of rivers. Shipworms did not make an appearance in Groningen (across the border in the Netherlands) until well after the initial outbreak in the 1730s. That said, they would eventually infest the Dollard region, even popping up near the town of Delfzijl. It would be interesting to determine whether similar paaldijken were constructed further from the Eems river, and thus more susceptible to infestation.

The second point related to the Christmas Flood of 1717, a massively destructive early modern disaster which devastated large areas of the northern German and northern Dutch coastlines. Jarssum’s paaldijk was likewise affected. Using historical sources (in particular cartographic material), the presenters showed

Homann’s map of the inundated regions of the Southern Sea and Wadden sea areas (in brown). Geographische Vorstellung der jämmerlichen WASSER-FLUTT in NIEDERTEUTSCHLAND, welche den 25.Dec. Ao. 1717, in der heiligen Christ-Nacht, mit unzählichen Schaden und Verlust vieler tausend Menschen einen großen theil derer Hertzogth. HOLSTEIN und BREMEN, die Grafsch. OLDENBURG, FRISLANDT, GRÖNINGEN und NORT-HOLLAND überschwemmet hat. Source: http://www.ich-war-hier.de/wp-content/uploads/2012/03/P1040061.jpg

damaged caused by the Weihnachtsflut and its subsequent repair. Contemporary German and Dutch sources often reference the use of ships to block the largest dike breaches and contemporary maps of the disaster actually show these ships on the maps themselves! Johann Baptiste Homann’s 1718 map of the Christmas Flood is perhaps the best-known example and it likewise depicts these iconic ships.

To my knowledge, little scholarship exists on this fascinating source material. Although maps are often used in historical research (and apparently even MORE frequently in archaeology), disaster cartography, especially from the early modern period, is underdeveloped. This presentation provided further confirmation that more research into this subject is necessary.

The second half of the conference tended to focus on the early modern and modern, rather than the medieval past. Menne Kosian of the Rijksdienst Cultureel Erfgoed gave a general overview of what he termed the “schizophrenic” relationship between the Dutch and water. My own presentation covered the first phase of the shipworms epidemic between 1730-33 through the lens of “causal storytelling” (see blog for transcript) and Miranda de Wit of the engineering bureau MUG laid out her findings related to a 17^th-18^th century sluice in Drenthe. The final two presentations brought us into the modern period. The final two presentations were less historical or archaeological case studies, than “state of the field” talks. Michel Lascaris of the Rijksdienst Cultureel Erfgoed in Amersfoort and Michiel Bartels of Archeologie West-Friesland showed the audience the two faces of dikes as cultural heritage. On the one hand, dikes are living relics of the past. They reveal changing patterns of spatial development and settlement; they are artifacts of disasters and demographic changes; and they are material evidence of the historic relationship between humanity and the environment. Dikes, in other words, are archives. Dikes are also water protection, however. They are a necessary boundary between the sea and an (increasingly) vulnerable population. Lascaris and Bartels showcased the cultural value of dikes by highlighting their diversity and the special challenges cultural heritage and archaeological organizations face when attempting to use, explore, promote, and protect these unique structures.

In the final panel presentation, which featured Van Dam, Bartels, Lascaris, Keunen, and Van den Brink, the audience was offered the opportunity to comment on some of the larger questions addressed over the course of the day (and some that weren’t). Of particular interest to me were Van Dam’s comments about the importance of storytelling in the context of dikes. Drawing a distinction between archeological and historical scholarship, Van Dam made the case for argument and narrative as compelling components of dike research. From my own perspective is seems clear that dikes are more than just the physical remnants of past settlement. Dikes tell stories. They can reveal tragedies and showcase hubris.

The final panel takes questions from the audience.

Today, the historical value of dikes tends to be ignored by the public. Few actively recognize their ongoing use as water defense, leaving the job of managing their vulnerability to elected officials and engineers. Landowners may consider them barriers or obstructions (thus necessitating the official protections that conserve historically significant dikes like the Westfries Omringdijk). Even people who regularly use dikes for roads or recreation are frequently unaware of the history of these structures. This is where archeology, history, and historical geography have their greatest opportunity.

Last summer’s “open dike day” near Hoorn was very well attended by the public. Standing in the audience, people seemed to be fascinated by the process of discovery. They marveled at the depth of the excavation, and how the archaeologists pieced together the history of the structure with artifacts, historical documents and maps, and the guts of the dike itself. They were also interested, however, in the story of the dike. This included, of course, its historical story. The historical dispute that gave the Klamdijk its name, for instance, or its history of flooding and repair. Likewise, it also included the story of its future. Representatives of the local water board were on hand to discuss why a new pumping station (that opened up the possibility of excavating this protected space in the first place) was necessary in a climate changed future. The Open Dike day had cleverly married three stories: the story of the dikes past, the story of that history’s discovery, and the story of a potential future. Several of the presentations from Dijken, Dammen en Duikers likewise told stories. Grounded in evidence, they both engaged the public and inspired further questioning. Taken as a whole, the conference did so as well. The coda to this conference was the public unveiling of Dwars door de Dijk. My hope is that this work, like the conference it concluded, serves as a bridge between disciplines and between publics. Dikes appeal to a number of metaphors, and perhaps that blunt involve allusions to separateness, compartmentalization, and division. But as Roos van Oosten, the chairwoman of the Stichting Middeleeuwse Archeologie, also noted in her introductory remarks, dikes have in the past been the embodiment of cooperation and productive communal ambition. It was a fitting conclusion, I thought, that Van Oosten returned to this image and this same spirit (this time in the context of scholarship) at the closing of the conference.

Image from the Heidelberger Saksenspiegel depicting the communal constructing of a medieval sod dike (14th century)

Terug in Nederland! It’s been a little under a year, but I’m back in Holland. It’s been a little under a year, but the research blog is back. I was warned that teaching occupies a large share of one’s time as a first-year professor. Creighton (and the move to Omaha) offered a multitude of distractions, from service opportunities to student seminars, to conference presentations, to settling into a new city/new state.

Happily, one of the products of last years research trip has finally seen the light of day. The research workshop “Resilience in disastrous times: the processing of historical catastrophes in the Low Countries (ca. 1600-1850)” resulted an edited volume in the interdisciplinary journal of Low Countries Studies, Dutch Crossing. The collection includes work from Raingard Esser on resilience to seventeenth century flooding and Marijke Meijer Drees’ contribution thoughtfully reconsiders the role of providential thinking (a particular fascination of mine) in the context of the Delft gunpowder explosion of 1654. Joop Koopmans and myself discuss shipworms. Koopmans considers the role of media (in particular newspapers, periodicals, and pamphlets) in the early years of the epidemic, and my own article addresses the paalwormepidemie in the context of disaster novelty.

Finally, Lotte Jensen brings us in to the 19th century with her analysis of Louis Napoleon’s complicated relationship with his subjects, especially in the context of his management of disasters. Naturally, it’s nice to see a project completed to my satisfaction. The research into shipworms is far from over (stay tuned for more info on the subject), but I’m excited expand the work in new directions in the coming month.

Like last year, this blog will document my travels, my research, and my thinking about subjects related to my research on Dutch 18th century disaster. My schedule this summer is much less focused on conferences. Aside from a presentation in late June sponsored by the Stichting voor de Middeleeuwse Archeologie in Hoorn (NL), my schedule is almost completely dictated by my research needs. My research goals for this summer will touch on several themes, but will largely be focused on three subjects:

1. Gathering further evidence of shipworms infestations, especially those prior to 1730 (for instance, on the island Goeree in 1728)
2. Collecting cattle plague mortality data. This work relates to a collaborative research project independent of my manuscript with Filip van Roosbreuck.
3. Collecting archival source material on the Dutch River floods of 1740-41. This final goal will dominate my time and will lay the foundation for a collaborative paper with Toon Bosch and (possibly) a final case study for my manuscript.

One can’t work all the time, though! It’s the weekend and I’ve just finished a long standing project (more on that to come). I’m off to Gelderland for some lekker fietsen!

I’ve been in Holland for more than a week, but up until today, I couldn’t honestly say that my “research” trip had begun. Between conferences, excursions with colleagues, writing lectures, and weekends (when the archives aren’t open), I’ve had little time to do anything else. That changed this week when I was able to visit the Zeeuws Archief in the province of Zeeland. Zeeland is a province of islands-cum-peninsulas. For much of its geological history, Zeeland was disconnected, but over the last several centuries, the Dutch have expanded the boundaries of these islands and linked them together with massive polders. Today, these interconnections appear like gnarled fingers extending out from the southwest of the Netherlands.

Zeeland is the furthest southern maritime province of the Netherlands and during the Golden Age, it was the second most prosperous after Holland. It is also one of the provinces I have the least experience with, having only made one prior research visit and one visit for fun. Luckily, my friends Nick Cunigan (studying at the UvA on a Fulbright grant) and his wife Beth also planned on visiting Zeeland. Nick was planning an archival trip as well and since they were staying with family friends in Middelburg (the capital), I decided to tag along and extend my trip to two days.

Although archives are often located in or near the places that their documents describe, I am rarely able to both see the historical traces of past places in the archives and then physically step into them on the same day. This was precisely what I did on the Zeeuws island of Walcheren near the village of Westkapelle. Westkapelle, despite it tiny size and relatively modern appearance, has a deep history. It is one of the most western cities in the Netherlands because it is nestled in a nub of Walcheren that extends into the North Sea. The island has changed size and shape over a millennium and is actually the second Westkapelle (the first, called “Old Westkapelle,” was lost in the 14^th century and is one of the many “drowned villages” of the Netherlands). The fate of its unlucky predecessor is unsurprising if one considers Westkapelle’s location. The town lies at the intersection of two steep dune ridges that almost meet at the western tip of Walcheren. They don’t quite conjoin however, and in that gap lies Westkapelle. It is a perfect location to tap the wealth and trade opportunities of the North Sea, but it is also incredibly vulnerable to storm surges. I travelled to the archives in Zeeland largely to study this city and its struggle with the sea.

The ultra modern Zeeuws Archief, built into the side of a 17th century brewery.

Flooding is without a doubt a formative element of Dutch history and identity. In a country whose wealthiest areas lie below sea level, flooding and flood protection (in particular dikes) are inseparably connected to broader national narratives of Dutch economic success, culture, and even social structure. Dikes protect against the sea, but they are also costly, they require complex communal arrangements to build and maintain, and when they break, they signify a challenge to those same structures needed to erect them. The Westkapelle sea dike is a case study in these challenges. Located at such a vulnerable location, the tip so to speak of the Netherlands, the dike was the vanguard of coastal protection in the early modern period. Although it now appears massive (at “deltahoogte” or a 1/4,000 year change of flooding), the sea dike was much lower in the eighteenth century. It linked the two dune ridges that flanked its northern and southern edges. The dike and its dunes were both highly susceptible to the erosive force of the waves, however, so by the 16^th century, inhabitants began building wood, reed, and stone wave breakers to protect the coast. These staketwerken sometimes ran parallel, but on the Westkapelle sea dike also extended out perpendicular to the sea to act as wave breakers (below). A technological achievement in dike protection, these structures were also a fantastic habitat for a new type of biological disaster that hit the Netherlands in the 1730s.

You can see the staketwerken extending westward from the dike likes spikes. From: Tirion/Hatinga, Plattegrond van het eiland Walcheren in de 18e eeuw, 1754

The naval shipworm (Teredo navalis) is a marine mollusk species of unknown geographic origin (called a cryptogenic species) that bores into wooden structures. They spend nearly their entire lives in the tiny caverns they eat into submerged wood and, because they had a particular taste for ships (thus the name), they have been a serious challenge for European mariners since antiquity. They are also a classic fouling species that hitches rides on ships hulls to populate new coastal habitats. Their success and wide distribution prevent any conclusive judgement about their origins, especially since they are only one of several shipworm species and they are difficult to differentiate from other marine borers. Their arrival in the Netherlands was unusually dramatic, however, and the preponderance of documentation about the invasion marks this event as a unique opportunity to study the cultural, technological, and social response to a marine invasive species.

When shipworms arrived in the Netherlands in the fall of 1730, their populations exploded. Not content with ship hulls, they attacked sluice gates, harbor revetments, and sea dike protections like the staketwerken in Westkapelle. Multiple shipworms could infest a single wooden pile driven into the sea, and during storms, the force of the waves would snap the now weakened wood. Zeeland was not the only province to employ wooden wave breakers, and dike inspectors throughout the coastal Netherlands discovered similar infestations in their own constructions. People panicked. They wrote religious treatises condemning the arrival of the “worm” as a punishment sent from God, they wrote natural historical treatises on the species, and dike engineers experimented with new shipworm-proof dike designs. Ultimately, the shipworm epidemic touch off a fundamental redesign of dikes throughout the coastal Netherlands.

Under-girding much of this response were several basic questions. Why did the shipworms appear? Why were they in certain places, but not others, and why did they appear at the particular time they did? I investigated these questions both from a modern and eighteenth-century perspective in my dissertation in the context of Holland, but I wanted a comparative study. Zeeland, and the Westkapelle sea dike in particular, was perfect because it was the location of the first known outbreak.

Teredo navails (the naval shipworm) on display at the Fries Museum in Leeuwarden

Shipworms thrive within a defined set of ecological limits, the most important of which are salinity, temperature, and habitat availability. I had already dealt with issues of temperature and salinity in the past using GIS in a separate project, but a new element I’ve begun investigating is their habitat. Shipworms did not infest all wooden structures on the coasts of the Netherlands, they didn’t even affect all of the wood in those areas with suitable salinity and temperature. Infestations clustered around large ports with contacts to the tropics (evidence I have taken to justify their invasive origin). This explains their location, but it doesn’t explain the timing. Why in the 1730s and not before? Drought was likely a part of the answer. The early 1730s were unusually dry and the reduced river output would have heightened salinity and created more ideal breeding areas for the mollusks.

The 1730s were not the only drought period since ships began returning from the tropics, however. Why didn’t shipworms appear during these earlier era of low river output? I suspect that the answer probably lays in a combination of environmental and human factors, including the expansion of their wooden habitat. Staketwerken in Zeeland, paaldijken (a sort of wooden palisade that fronts dikes in Holland), and wierdijken (a wood and seagrass construction) in West Friesland) would have been ideal habitats for these wood-boring mollusks. Unfortunately, each of these dike constructions predated the shipworms by centuries. What is unclear is the scale at which they were built. Were these structures only used to reinforce the most vulnerable areas of the coastal Netherlands, an thus only offering limited habitat? Their expense demanded vast resources, and since the half century leading up to the 1730s was a period of relative economic stagnation in the Netherlands, they would not have been built without serious need. Money was the principle limiting factor for the expansion of these protections, and as a result, also a limiting factor for shipworms.

Shipworms pictured in Holland next to harbor revetments. Dike workers are shown removing the infested wooden piles.Paalwormen die de dijkbeschoeiïngen aantasten, 1731, Abraham Zeeman, 1731 – 1733

This same period also witnessed accelerating ecological changes, however. The shifting dunes of Walcheren (a serious problem in the 1720s) and the erosion of land in front of dikes (a serious problem in shipworm-infested West Friesland and on Walcheren) expanded the vulnerability of these regions. The Dutch would have found themselves in the awkward position of needing to drastically expand their system of coastal protection (what Petra van Dam refers to as the “hardening” the land-sea border) while at the same time having limited financial means to do so.

Where will this line of research take me from here? Two directions. First, I will map out the potential habitat for affected regions of the Netherlands. Where exactly were the coastal regions of the Netherlands affected by shipworms? Contemporary maps sometimes contain this information, which I can then digitize and integrate into a larger model of shipworm suitability that includes salinity. I will also try to tease out how the Dutch on Walcheren, as well as other regions, managed to negotiate this difficult economic/environmental situation in which they found themselves by the 1730s. Did they expand their use of wood? If so, by how much? These are difficult questions, but the trip to Walcheren was the first step.

Standing on the modern Westkapelle sea dike.

That step included literally walking on the now asphalt coated Westkapelle sea dike. It’s now massive and one can barely see the lighthouse in the city from the other side of the dike. It seems an impenetrable barrier and its easy to forget how recent this monumental new iteration of the sea dike actually is. At the end of my first day in the archives, I was excited to finally see the dike I’d been reading about. What I couldn’t have expected was that everything about this area belies its past. It is now a resort town. Dutch and German vacationers sun themselves on the beach (though obviously not on the cloudy day that I visited) and surfers swim out from shore to catch remarkably low waves. Driving through the modern Westkapelle village (while catching a brass band play the Band of Brothers theme song at a public concert), its easy to forget that this now quaint seaside village was once the site of a massive invasion. This history is now buried in the dikes. Before I left, though, I looked out to shore and noticed some dark shapes in the water. It was high tide, but appearing intermittently between the cresting waters, were large wooden piles. Westkapelle still uses wave breakers. I would only have to wait until low tide. With patience, I would see them.

Resilience is the new buzzword for historians who study disaster. How do societies respond to adverse weather, disease, or warfare? What conditions prompt successful rebounding from catastrophe? How can one measure the differences between one group of peoples’ responses from another? These questions drive the sub-field and the many recent publications, conference panels, new research groups, and the workshop which is the subject of this post demonstrate its growing vogue.

Although disaster history is a relatively new field, having only come into its own over the past ten to fifteen years, it had already witnessed the rise and fall of several similar terms that promised to unify the field under a common set of goals, themes, or subjects. Adaptation (and adaptive capacity), vulnerability and risk, and memory have each enjoyed their moment in the sun and to a greater or lesser extent, continue to exert influence on the field. The current focus on resilience follows in a similar vein by drawing explicitly on social scientific and contemporary policy concerns.

Disaster research (including historical) tends to follow trends in policy. Climate policy in particular has driven the push for greater attention to resilience in research.

In particular, resilience scholarship promises to offer new interpretations on how past societies created durable and sustainable social, technological, or cultural relationships in the context of environmental change. The relationship between resilience and “sustainability” (an even more powerful and politically resonant buzzword) can also offer interesting and valuable insights into modern problems associated with disaster and sustainability. Look to past, the proponents of this subject argue, for models for future behavior. As a result, it is not unusual to see resilience-oriented studies pop up in the context of larger initiatives focused on issues of sustainability, both in policy-relevant contemporary contexts and in history. The Rijksuniversiteit Groningen’s research group “Sustainable Societies: Past and Present,” for example, is housed in the Research Centre for Historical Studies and grounded in a similar ambition.

Resilience has not been an important element of my research in the past, although the cultural and technological response to nature-induced disasters is a central element of my dissertation. Partly, this is because the same conditions that make “resilience” such an engaging buzzword (i.e. its policy-relevant, modern, economic and social characteristics) make it a difficult term to adapt in premodern times. Rather than tackle the subject head on, I dealt with constituent elements that I could more easily harness (like memory and learning from disasters). As a result, I completed the project on schedule (my primarily goal all along), but my failure to examine disasters in way that explicitly offers useful lessons for disasters in the present has always been rather disappointing. This is why I was intrigued by the invitation to present my research at a workshop called “Resilience in disastrous times: the processing of historical catastrophes in the Low Countries (ca. 1600-1850)” at the Rijksuniversiteit Groningen (RUG).

The workshop promised to examine resilience (weerbaarheid) from a cultural context. How did people write about disasters and could those writings also work as coping strategies? How were disasters remembered, or mis-remembered? What types of media conveyed that information? What dialogues did people employ to explain disaster? Finally, and perhaps most importantly, how did each of these ways of interpreting the culture of disaster accommodate or determine the practicalities of bouncing back from catastrophe? This last point was of particular importance to me. Cultural history is saddled with the (in my opinion) undeserved reputation of seeming unanalytical, vague, and impressionistic. Cultural history can also work in a realm beyond description, and I try in my work to use culture as both context and the driver of social, technological, and even environmental change.

Presenters came primarily from the RUG, with myself, Lotte Jensen from Radboud Universiteit Nijmegen and Petra van Dam of the Vrije Universiteit Amsterdam excepted. A number of research masters and PhD students as well as other faculty joined the conversation as well. We would each have about 30 minutes for presentation and discussion of our work. There would be a welcome by one of the co-organizers Marijke Meijer Drees as well as opening and closing remarks.

Although resilience is a popular subject in disaster scholarship, one cannot make a similar judgment in the context of the Netherlands. Disaster scholarship is a strong field in Germany and Switzerland, the introductory speaker Raingard Esser noted, but Dutch scholarship largely lacks a similar history of involvement. Although Dutch history has been punctuated by persistent (sometimes catastrophic) disasters, and although many historians acknowledge the cultural power of (in particular) flooding, catastrophe does not occupy a position of cultural force in Dutch scholarship. This has always seemed somewhat surprising to me. Disaster has played a prominent role in the Netherlands’ strong traditions of social and economic history, as well as historical geography. Of the few environmental historians working in the Netherlands, several of them specialize in disaster or disaster-related fields as well. That said, the study of historical disaster & culture is underdeveloped. That this workshop happened at all may be a good indication that times are changing.

Each of the speakers offered fascinating glimpses into the history of Dutch disasters, stretching from the medieval past to the 19^th century. Following Esser’s introductory framing of cultural disaster history, Drees presented her work on continuity and change across disaster narratives, particularly in the context of poetry. She highlighted several different types of disasters (and unlike many other presenters) included different geographic regions, for instance the London Fire (1666) and the Delft Gunpowder Explosion (1654). What was fascinating to me was the manner in which Dutch observers not only recycled literary themes, but also visual themes int their disaster print making – showing again the power of this type of cultural inertia.

Joop Koopmans followed Drees with his own preliminary work on the shipworm epidemic and media response. He focused primarily on Dutch newspapers and employed the new Delpher tool with the KB to great effect. Delpher is an ongoing digitization initiative at the Koninklijke Bibliotheek in The Hague. It allows remote users to access full-text copies of Dutch periodicals, books, as well as newspapers going back to the 17th century. His work was particularly helpful for me, not only because we both presented on shipworms, but because his focus on the media impressions of the worms was a subject I had never explicitly dealt with. Following the lunch break, I presented my own work on the shipworm epidemic of the 1730s, in particular it role as a novel biological invasive. I argued this novelty was a crucial explanatory variable that helped explain the decision-making process.

Lotte Jensen followed the pair of shipworm presentations with her own work on disasters and collective identity fashioning in the era of Louis Napoleon (1806-1810). She argued that news accounts and visual images used disasters to either boost the popularity of the French King or denounce the French occupation. Finally, Petra van Dam presented work on the disaster relief efforts in the wake of the river floods of the 19^th century. She also worked in the context of Dutch newspapers and archival material and investigated the meaning of lists of relief donations and lotteries. She found that there were profound continuities between the cultures of relief action in the past into the 19^th century, particularly their relationship to established (religious) aid organizations.

The workshop was a fascinating break from the type of research agenda I’ve had in the past. I have never been to a Dutch workshop and its informality, welcoming nature, and (of course) the borreltje at the end fostered a warm and inviting atmosphere. It was also a fascinating intellectual exercise, particularly because the cultural context of Dutch disaster is so little understood. What would be truly interesting is to compare the findings of this workshop with work from other areas in Europe or around the world that have enjoyed greater attention to the culture of disaster in their scholarship. The mystique of early modern Dutch history has always been grounded in some recognition (albeit highly contested) of Dutch exceptionality. But was there something truly unique about Dutch cultural response to disaster? This question will have to be left to future workshops with a more comparative bent. In the meantime, perhaps this event is a hint that we might expect a greater interest and participation in historical disaster studies and culture in future.