With the outbreak of World War I, von Gündell was recalled back to active service and appointed Commanding General of the V Reserve Corps. His Reserve Corps was assigned to the Fifth Army and fought at the Battle of the Ardennes, and during the siege of Verdun. Gündell received an active commission with his previous rank on 2 September 1914. In February 1916 his Corps went from trench warfare around Verdun to the offensive. His unit suffered heavy losses during the battle at Fort Vaux and its surrounding village, and eventually had to withdraw from the front in mid-June. It was transferred to Champagne for refitting. For the fighting at Verdun, von Gündell was recognized and awarded the Pour le Mérite on 28 August 1916.