In May 1915, the French 10th Army managed to reach the top of Vimy Ridge, a strategic position commanding the approaches to the coal-mining centres of Lens and Loos, but were driven off by ferocious German bombardment. In September, General Foch determined to try again while also commanding a new offensive to the south at Champagne. Coordinating the two attacks produced delays which enabled the Germans to reinforce and prepare second lines of defence. When the offensive began on 25 September it met with initial success, but the German rear defences held, and diversion of manpower and artillery to the southern thrust undermined hopes of a critical breakthrough. The assault on the ridge itself faltered when the British needed reinforcements for their attack on Loos. Concrete gains were made and held, including the Fort at Souchez, but the Vimy Ridge stayed in German hands.