way, they would soon be flooded out;" Van Coehoorn argued the high water table common in the Netherlands negated the danger posed by mining, and thus he required only two-thirds of the materials needed for similar French fortifications. Water was another feature of his work; although completed years after his death, he designed the Zuider Waterlinie between Sluis and Nijmegen. His recommendation of a defensive barrier in the east, using the IJssel and the Dutch portion of the Lower Rhine, formed the basis of a NATO defence line built in the 1950s, codenamed Plans 'C' for Coehoorn and 'D' for Deventer. Namur; the Sieges of 1692 and 1695 His ideas remained untested until the 1688-1697 Nine Years War, whose tactics placed great emphasis on manoeuvre and siege warfare. He was present at the capture of Kaiserswerth and Bonn in 1690; his role is unclear but Frederick I offered him a position as Major-General in the Prussian army, which he refused. Van Coehoorn was finally able to implement his ideas when appointed commander of Namur in 1691. Namur was divided between the 'City', on the flat northern bank of the river Sambre, with the 'Citadel' on high ground to the south controlling access to the rivers Sambre and Meuse. He strengthened the 'inner' Citadel with new outworks at Fort William and La Casotte, but did not have time to do the same for the 'outer' City area. The garrison of 5,000 was too small for an active defence, while many were poorly trained and motivated Spanish troops. In the 1692 Siege of Namur, the City fell in less than five days, but the Citadel and its 500 Dutch defenders held out until 30 June. This was largely due to the terms negotiated when Van Coehoorn surrendered the City; he agreed not to fire on the City from the Citadel, in return for the French not attacking from that direction. As Vauban pointed out, this made it almost impregnable. Regardless, the defence was a significant achievement and William III made him Major-General and commander of the vital city of Liège. He also supervised the construction of new defences at Huy, which the Dutch lost in July 1693, then recaptured in September 1694. The focus of the 1695 Allied campaign was the second Siege of Namur. The fortifications had been strengthened by Vauban, while Marshall Boufflers had a garrison of 13,000. Van Coehoorn