Grenzschlachten
On the outbreak of World War I, Foch was in command of XX Corps, part of the Second Army of General de Castelnau. On 14 August the Corps advanced towards the Sarrebourg–Morhange line, taking heavy casualties in the Battle of the Frontiers. The defeat of the XV Corps to its right forced Foch into retreat. Foch acquitted himself well, covering the withdrawal to Nancy and the Charmes Gap before launching a counter-attack that prevented the Germans from crossing the River Meurthe.