On the morning of 10 May 1940, German paratroopers landed in the adjacent Bonnepolder and were deployed with air landing troops. It was a navigational error, as they were supposed to reach the Hague to capture the Queen and the Cabinet. A group of about 130 German soldiers dug in at the edge of the forest, waiting for further orders. The Dutch defenders fired cannons from the island of Rozenburg and the old Fort Maasmond and also launched some ground attacks, which the well-armed German troops managed to repel. After five days of fighting, the Netherlands capitulated.
Colonel Erich Neumann commanded the German troops in Festung Hoek Van Holland. He was a zealous officer who often had his men train rigorously. The war-torn forest came into their focus again at the end of 1942. On the east side, they established the headquarters of the Festung. Seventeen large bunkers were built in a ring formation. They housed troops and ammunition, and there was also a large command bunker and a hospital bunker with surgical facilities. They were painted in various camouflage patterns and covered with large nets. Among the trees, the large complex was difficult to spot. A washhouse and a large brick hall for recreational activities were also constructed.
After the war, the Royal Netherlands Navy used the bunkers as an ammunition depot. Signs reading “Gevaar Radioactieve Stoffen” (Danger Radioactive Materials) led to rumors that nuclear warheads were stored there. In the 1980s, the ammunition complex was decommissioned and the forest transferred to the Zuid-Hollands Landschap. A brick entrance gate with a guardhouse at the Staelduinlaan parking lot still recalls the Dutch army presence.
The washhouse and hall were demolished at the beginning of this century. The other bunkers have been preserved but are now closed, as they form part of a bat reserve. The protected mammals hibernate in the mild, humid climate inside the bunkers and benefit from peace and quiet. From the walking paths, you can still see the exterior of the enormous moss-covered concrete structures. They are easiest to observe in winter when the trees have no leaves, but in summer, it is impressive how fully they merge with nature.
In the northeastern corner of the forest stands a second, smaller German bunkerized headquarters. It housed a subordinate company and is visible only through the fence from the road. Roughly in the middle of the forest is the visitors’ center d’Oude Koestal. During the war, the Germans requisitioned the farmhouse and stable. On the high dune nearby there was once a lookout tower from which one could see over the trees to the Nieuwe Waterweg. An anti-aircraft gun was placed next to it.
In the far west of the forest stand a concrete personnel shelter and a garage for anti-tank artillery. Nearby, hidden among dense shrubs, are brick structures for troops, provisions, water, and ammunition. They were part of a light field battery. The German gunners were expected to fire from the forest onto the beaches where Allied landing craft would disembark troops, or so the plan went.