‘Veilig’ achter water: De interactie tussen getijprocessen en militaire aanwezigheid in de vorming van een landschap: de geschiedenis van militaire inundaties in Noord-Vlaanderen (circa 1300 – 1945).

The theme of this PhD thesis is how the uses and consequences of the inundation weapon influenced the landscape formation of North Flanders for 650 years. To this end, all military inundations during that period have been investigated in this area. Human actions include the cutting of dikes, reclamation works, and the construction and use of infrastructure works. The natural factors such as the geomorphology and the tide partly dictated the way in which flooding events took place and infrastructure was constructed but was continuously adapted to military developments. The human influence grew steadily over the centuries in this area. Various developments occurred in the establishment of military inundations. The first development concerns the type of water used for flooding. It began with occasional ad hoc saltwater inundations to evolve into combined saltwater-on-freshwater inundations. Secondly, there was a related development, from the cutting of dikes through the use of cuttings with thresholds to the use of sea sluices under military supervision, which could both ingest seawater and retain freshwater in basins. A third development was strategic. From the Eighty Years' War until the nineteenth century, the starting point was to maintain a cross-border connected water line from west to east. This water line was created after a number of dike cuttings in 1583-1586. Initially, the starting point was maintaining a water line in the tidal area, but following the construction of major military land reclamations between 1780 and 1790, this approach was abandoned as the primary line of defense. Since 1700 there had been a total vision of the military defense strategy for the area. However, no comprehensive defense plan was fully implemented and the focus continued to be on partial aspects. The plans mentioned did serve as a source of inspiration for later military strategists. Until the ‘modern’ era the choice of fresh or sea water remained a matter of speed, in short sufficient supply. Alongside these developments, an active attempt was made to optimize the defense value of the inundated area with infrastructure. Where land restoration took place within the water line, military requirements regarding infrastructure were imposed upon the initiators of diking. Decision-making regarding flooding and the construction of infrastructure also underwent a process of development. In the relationship between the military flooding strategy and the landscape, various developments and patterns are observable in terms of the areas of the inundations, the types of inundations and the impact of the inundations on the landscape in both the short and the long term. Comparing the North Flemish water lines with those elsewhere in the Low Countries, the differences are particularly striking. For instance, virtually all flooding methods were often applied alongside each other and in a complementary manner. This variation was partly the result of a landscape development in which, due to the unstoppable sedimentation, the tidal landscape often had to be given up to a polder in a manner guided by military considerations. However, the tides continued to exert an influence even after that. The area had a different strategic use, with the various parties alternately using the infrastructure offensively and defensively. In addition, the area has been troubled by wars at least ten times since the Eighty Years' War, so it was forced to function as a testing ground where experiments were conducted by a very dynamic tide with all kinds of water-based forms of defense. The special dynamics described above between human action and natural factors have been characteristic in the creation and development of the military landscape, particularly of the military inundation landscape, as a weapon in both peace and wartime in North Flanders.