The Dyle Plan or Plan D was the plan of the Commander-in-Chief of the French Army, Général d'armée Maurice Gamelin, to defeat a German attempt to invade France through Belgium. The Dyle (Dijle) river is 86 km (53 mi) long, from Houtain-le-Val through Flemish Brabant and Antwerp; Gamelin intended French, British and Belgian troops to halt a German invasion force along the line of the river. The Franco-Belgian Accord of 1920 had co-ordinated communication and fortification efforts of both armies. The Belgian government let the accord lapse after the German Remilitarization of the Rhineland on 7 March 1936, to adopt a policy of strict neutrality, with the German Army (Heer) now on the German–Belgian border.