The XXI Indian Corps was first raised on 12 August 1917 during the World War I, specifically for operations in the Middle East region against the German–Ottoman alliance.

The corps was part of the Egyptian Expeditionary Force under Allenby and took active part in the capture of Gaza and Jerusalem from October to December 1917, and against the Turkish Seventh and Eight Armies in 1918.

[2] The corps was re-raised in Persia on 6 June 1942 as a formation of the Indian Army during World War II.

The corps was commanded throughout its existence by Lieutenant General Mosley Mayne and was part of the Tenth Army.

The corps, composed of the 8th Indian Infantry Division (Major-General Dudley Russell) and the British 56th Infantry Division (Major-General Eric Miles), was created as part of the Allied buildup of forces in Persia and Iraq to create Persia and Iraq Command in order to prevent a German invasion of the Caucasus.