The Grebbe Line (Dutch: Grebbelinie) was a forward defence line of the Dutch Water Line, based on inundation. The Grebbe Line ran from the Grebbeberg in Rhenen northwards until the IJsselmeer. Early history and first decommissioning The Grebbe Line was first established in 1745 as a line of defense 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 for that purpose; an attempt was made in 1794 to establish a defensive line against the invading French army under General Jean-Charles Pichegru, but the joint British-Dutch army abandoned the line when the French troops approached. Throughout the 19th century, the Grebbe line was maintained as a defensive line. However, since no attacks appeared likely, it was deemed less necessary to maintain the costly fortifications, and in 1926, a large part of the fortifications was decommissioned. World War II In 1939 the disused line was once again fortified against a German attack on the Netherlands, but due to cost issues reinforcements never reached an acceptable level. In the extensive 1939-defence plans, in which the Grebbeline would be provided with more extensive and much denser concrete reinforcements, the line would fulfill its ancient task as a forward line of defensive. These plans would however never be executed, surpassed as they were by the events of the German invasion in May 1940. The Grebbeline by that time had been largely constructed behind vast inundations, after which a front line lay that was composed of classic trench works mixed with ferro and ferro-concrete bunkers of light and medium grade. The front-line trenches had hardly any depth and contained only half a battalion of infantry per single km of stretched line. Behind this front-line was a second row of trenches which had the function of a blocking defence should the front-line be penetrated. Reserves could be thrown in from this line and behind it were battalion and regimental CP's as well as forward light artillery positions. More to the rear were the medium and heavy artillery positions as well as divisional reserves. The Grebbeline had two weak spots. The first two were near the city of Amersfoort, the third one near the village Rhenen, where the elevated Grebbeberg - a 150 feet high elevation - had made inundation works impossible. These