The Ersatz Corps (German: Ersatzkorps) was a corps level command of the German Army that existed briefly at the beginning of World War I.

General der Infanterie Ludwig von Falkenhausen was brought out of retirement to take command during its brief existence .

Ersatz divisions were formed on mobilisation from replacement units of active regiments.

Cavalry Ersatz Abteilungen and Field Artillery Ersatz Abteilungen were likewise formed from active cavalry and field artillery regiments.

Armee-Abteilung Falkenhausen[4] was set up in the southern part of the Western Front in Alsace-Lorraine on 17 September 1914 from the parts of 6th Army that remained in Lorraine after the main body marched north to participate in the Race to the Sea.