More than 30 percent of the floods of the past 500 years in the southwest of the Netherlands were caused deliberately. During wartime, areas of land were regularly flooded to stop or chase the enemy. This is the conclusion of researcher historical geography Adriaan de Kraker (VU University Amsterdam).
Risk Tactic
In wartime, experts often pointed out the places where a dyke breach would have the maximum effect. However, plans for the restoration of the dikes after the planned flood were mostly lacking. As a result, the dikes often remained damaged for decades, or were even not repaired at all. The consequences of the floods are therefore still visible in many places in the landscape. Tidal channels such as the Saeftingher Gat, Hellegat, Braakman and Havengat in Zeeuws-Vlaanderen were created as a result of the flooding in the 1580s. Sludge deposition formed thick fertile clay soils. Due to the long presence of the salt water, salinization of the soil occurred here and there.
“Causing a flood is a risky tactic,” says De Kraker. “It only works well in combination with a well-considered plan, including rapid repair of the dikes and compensation for the damage caused to the victims. However, nothing had been arranged for this, my research showed.” If money was made available for this, for example after the floods caused by the Dutch rebels during the Eighty Years' War to thwart the Spaniards, this was often used for military purposes instead of repair work. De Kraker published his findings in the journal Hydrology and Earth System Sciences .
More and more strategic
De Kraker conducted his research on the basis of historical sources. Such as historical maps, reports of damage to dikes, reports of seawall maintenance and correspondence from people who were involved in one way or another in the flooding. The fact that floods were used as a tactic in wars is not news in itself, says De Kraker. You can find it in all history books. However, De Kraker was the first to make a systematic overview of the consequences of the various types of flooding over the past 500 years. “But even before that, water was already an ally of humans in the fight against possible enemies,” says De Kraker. “Just think of the moats around medieval castles.”
The largest deliberately planned flood in De Kraker's study took place during the Eighty Years' War. Dutch rebels, led by William of Orange, flooded the Flemish part of the Western Scheldt to thwart the Spaniards. In 1584 and 1586 dykes were breached at Saeftinghe, Campen and Terneuzen, eventually two-thirds of Zeeuws-Vlaanderen was flooded.
Over time, the tactics of the flooded country became more and more strategic. In the 16 e and 17 e century, a cheerful flood was often a sudden inspiration or emergency. In the course of the 18 e century, special infrastructure was already being built in the Flemish part of Zeeland to be able to flood the country within a few days.
During the Second World War, water was used as a weapon in the Netherlands for the last time. In 1944 Walcheren was flooded by the Allies. On April 17, 1945, when the liberation was already near, the Germans flooded the Wieringermeerpolder for a while. More than 8,000 people had to look for a safe haven. This last inundation for war purposes in the Netherlands fell outside De Kraker's research area.
Fragment of polygon news from 1945, about the flooding of the Wieringermeerpolder. Source:NPO History, VPRO
Own agenda
Water is less suitable as a weapon for modern wars in our regions. After all, a fighter jet or bomber cannot be stopped by a flooded polder. “Yet even now, pieces of land are regularly flooded on purpose,” says De Kraker. “But then in the context of nature development.” The researcher would like to see nature developers make more use of the knowledge about the consequences of the flooding of the past and realize better what it means to give up a cultural landscape to the water.
As an example he mentions the line of defense that the Flemish in the 18 e century in the zone between the villages of Sluis and Doel. Some areas could be flooded there in the event of imminent danger. But it was precisely this area that silted up, so that the defense line eventually no longer worked. “Nature has its own agenda,” says De Kraker. “Both military personnel and nature developers have to take this into account.”
Neglect
Henk Weerts works as a researcher in physical geography and paleogeography at the Cultural Heritage Agency of the Netherlands and was not involved in the research. He is not surprised by De Kraker's findings. “The number of 30 percent does not surprise me. Just take the military inundations during the Eighty Years' War, which, among other things, caused the loss of the Drowned land of Saeftinghe.” Wars also indirectly caused flooding, Weerts notes. For example, the St. Elisabeth floods of 1421 and 1422, in which the Hoeksche Waard, the Biesbosch and parts of West Brabant were lost, were partly caused by neglect of the dykes during the Hoekse and Kabeljauwse Twisten. “Because of the war, there was no money to maintain the dikes.”