However, the French line was weak near the Ardennes forest. General Maurice Gamelin, when drafting the Dyle Plan, believed this region, with its rough terrain, would be an unlikely invasion route of German forces; if it were traversed, it would be done at a slow rate that would allow the French time to bring up reserves and counterattack. The German Army, having reformulated their plans from a repeat of the First World War-era plan, became aware of and exploited this weak point in the French defensive front. A rapid advance through the forest and across the River Meuse encircled much of the Allied forces, resulting in a sizeable force being evacuated at Dunkirk leaving the forces to the south unable to mount an effective resistance to the German invasion of France.