The Battle of the Grebbeberg () was a major engagement during the Battle of the Netherlands, which was a part of the World War II Operation Fall Gelb in 1940.
Background
In the 1930s, the Dutch government pursued a policy of strict neutrality. After World War I, the Dutch parliament supported a disarmament policy because it was generally thought that World War I had been "the war to end all wars". When the threat of Nazi Germany became more apparent the Dutch government decided to reinforce and retrain its Armed Forces.
General defensive strategy
In the 1930s the general defensive strategy was aimed at an attack by Germany. In that case the army should fall back on the Water Line, which formed part of Fortress Holland, the Dutch national redoubt. It was expected that assistance would then arrive from France and the United Kingdom. To defend the redoubt, it was necessary to slow the German advance down in order to give as many Dutch forces as possible the chance of assembling in Fortress Holland.
To this effect, several defensive lines had been constructed throughout the country. The Maas Line and the IJssel Line had been constructed along the Maas and IJssel rivers and served to detect German incursions into Dutch territory and to delay the Germans in the first hours of an invasion. The fortress at Kornwerderzand on the narrow Afsluitdijk guarded the northern approach to Fortress Holland while the Peel-Raam Line in North Brabant guarded the southern approach. Any attempt to approach Fortress Holland through the central part of the country would be delayed at the Grebbe line.
At the beginning of 1940, Chief of Staff General Henri Winkelman redesignated the Grebbe Line the Main Defence Line, because defending the East Front of Fortress Holland would bring the major city of Utrecht into the frontline and the enemy too close to the Dutch capital Amsterdam.
The Grebbe Line
The Grebbe Line was built in 1745 and had been used for the first time in 1794 against the French. It was maintained throughout the 19th century, but had been neglected ever since because it was thought to have become obsolete. In 1926, most fortifications were disbanded. When Germany became a potential threat the Dutch government had the Line recommissioned.
At the end of the 1930s, a series of pillboxes and casemates were constructed in the area south of the IJsselmeer and north of the Rhine. The Line was constructed according to French military principles from World War I which had proven to be successful then, but had, unknown at the time of construction, become obsolete. There were major flaws in the design of the pillboxes, which were difficult to defend against attack from the flanks and rear. The (fixed) weapons were antiquated, many of them dating back to World War I. Because the Dutch government did not want to antagonise local residents, permission to remove buildings and trees in the line of fire was refused, which greatly reduced the effectiveness of the defences and gave attackers plenty of cover. The trench system was also based on World War I principles. It consisted of a line of outposts (voorpostenlijn), a Frontline (frontlijn), a Stopline (stoplijn) and a Final Line (ruglijn).
The position at the Grebbeberg suffered from a lack of serious security measures. The government did not want to interrupt tourism as the local economy of Rhenen was dependent on revenues from the Ouwehands Dierenpark, a zoo located on a hill near Rhenen, the Grebbeberg. In the months leading up to the invasion, German officers in civilian clothes visited the zoo and used its lookout tower to survey the local defences. The government estimated that the Line would be completed in November 1940 and in May 1940 the bomb-proof pumping station at the Grebbeberg—which was necessary for the control of local flooding—had not been completed. Because of the lack of inundation, the German spies realised that the Grebbeberg would be a vulnerable spot in the Grebbe Line.
The opposing forces
The Grebbeberg was defended by the 8th Infantry Regiment (8 RI), Lieutenant Colonel Hennink. It was supported by a battalion of 19 RI. The defending units were part of the 4th division, Colonel van Loon. The 4th and 2nd division formed the 2nd army corps under Major General J. Harberts. On the Grebbeberg itself were 3 batteries of the 8th Artillery Regiment (8 RA), and three from the new 19 RA. Those of 8 RA were 1-I-8 RA and 2-I-8 RA armed with the 7 veld, and 2-III-8 RA with the 15 cm L/17 howitzer. Those of 19 RA were the three batteries of II-19 RA armed with the antique 12 cm Lang staal.