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Grebbe Line

The publication of Delacourt, entitled ' Maxims and Eeflections,' of which John de Witt himself had written two chapters and inspired others, recommended, so far back as the year 1668, the establishment of a fortified line to be carried in front of Utrecht and called the line of the Grebbe. No steps were taken at that period, though the Grand Pensionary had not awaited the rupture with France before completing works of defence.

The Grebbe Line was first established in 1745 as a defensive line to protect the Netherlands from invading armies. If an invasion was imminent, parts of the area between Spakenburg and the Grebbeberg were to be flooded. Until World War II it was never actually used in this purpose; an attempt was made in 1794 to establish a defensive line against the invading French army under General Charles Pichegru, but the joint English-Dutch army abandoned the line when the French troops approached. Throughout the 19th century the Grebbe line was maintained as a defensive line. However as no attacks seemed forthcoming it was deemed less necessary to maintain the costly fortifications, and in 1926 a large part of the fortifications was decommissioned.

In 1939 the disussed line was once again fortified against a German attack on the Netherlands, but due to cost and skills issues (soldiers were used as labourers) the earthworks were not well-constructed. In the original plans the line would fulfill its ancient task as a forward defensive line of the Water line. At the last moment however, in February 1940 the new Dutch commander in chief General Henri Winkelman, decided to make the Grebbe line the main defensive line in the central sector of the Dutch defences. The Dutch Water line was deemed less useful as the modern German field artillery could reach the main cities Utrecht and Amsterdam from their positions opposing the defences. Meanwhile, the Germans were aware of the line and of its outline. Before the war German spies had regularly visited the zoo at Rhenen using its lookout tower to map the defences there.

When the Germans attacked on 10 May 1940, the Dutch army managed to defend the Grebbe line for three consecutive days, much to the surprise of the Germans. The Dutch had intended to defend this line, but failed to inundate the foreground because of the rapidity of the German advance. By gaining the initiative, the Germans displayed their agility duringthe Battle of Flanders. Dutch, Belgian, British, and French forces, theirmisapplication of defensive posture now apparent, became reactors to Germanactivity. For example, the Dutch held the Grebbe Line until the thirteenth, when events farther south forced their withdrawal.

In 1942, examining the requirements for a suitable Allied assault area for a major operation to return to Europe, planners premised their study on the principle of concentration. The German beach defenses had to be capable of reduction by naval fire, air bombardment, or airborne troops. It was desirable, obviously, that the beach defenses be as weak as possible, but the essential thing was that there should be a reasonable chance of neutralizing them. This requirement, in fact, ruled out areas, such as the Netherlands, where the enemy could defend by large inundations which the Allies had no means of combatting. The Netherlands was ruled out because it was out of the range of fighter cover, because its beaches were too exposed and, being backed by sand dunes, had inadequate exits for vehicular traffic. Finally the Germans could too easily defend them by flooding.

On 19 April 1945 the Canadian First Army arrived on the coast of Ijssel Sea from Harderwijk to Kampen. The Germans withdrew south of the Sea to a defensive line about 25 miles long extending to the Waal River, and the front of which was covered by extensive inundations. They prepared to hold the territory in rear, including the great ports of Rotterdam and Amsterdam. A new operation was started by the Canadian Army on the 23d. Its mission was to capture Rotterdam and Amsterdam by destroying the German force holding those cities. A direct attack across the inundated ground between the Ijssel Sea and the Waal was considered impracticable. The German position, known as the Grebbe Line, had been planned and fortified by the Dutch. This time the foreground was well flooded. The new attack was north over the Rhine, about 6 miles west of Tiel. An initial bridgehead was established.