Assembling south of Le Mans on 13 August 1944, XII Corps began driving eastward and liberated the cities of Orléans and Châteaudun within five days. Moving rapidly against disorganized German resistance, the corps rapidly took Sens, Montargis, Troyes, Châlons-sur-Marne, and Vitry-le-François. By 31 August 1944, XII Corps had seized a bridgehead over the Meuse River at Commercy in Lorraine.