Assigned to France, Einem succeeded Gen. Max von Hausen as commander of the Third Army in September 1914. Successfully repulsing the French Champagne-Marne offensive from February–March and September–November 1915 respectively, Einem would take part in all three Battles of the Aisne and would hold Gen. Anthoine's 4th Army (under Gen. Philippe Petain's Center Army Group) during the Second Battle of the Aisne as part of the Nivelle Offensive from 16 April to 15 May 1917.