21 Corps was first raised on 12 Aug 1917, specifically for ops in Middle East against the Turko-German coalition during World War I. It took active part in the capture of Gaza and Jerusalem from Oct to Dec 1917, as part of Gen Allenby’s Army. Thereafter, intense ops were conducted against the Turkish Seventh and Eight Armies in 1918 alongwith other elements of Allenby’s Force, leading to annihilation of the Turks, the corps was disbanded in 1918, at the end of the war.

21 Corps was re-raised in Feb 1942, for ops in the Middle East. Initially the task of providing security to all installations in Iran and Iraq was allotted to the Corps. This also involved the task of ensuring sufficient oil supplies to Russia. Since the Axes threat to the area did not materialize, the fmns of 21 corps were dispatched to various other theaters of war. 21 Corps was de-mob at the end of Second World War.

HQ OFC, IPKF was org at Madras in Jul 1987, out of the Tac elements of HQ Southern Comd. Adv HQ was raised for OP PAWAN on 15 Apr 1986, with a truncated WE. The HQ directed active ops against LTTE for the liberation of Jaffna city and to est cont over North-East Sri Lanka. Final de-induction of IPKF took place by Mar 1990, signifying the termination of Op PAWAN. As a consequence thereof, orders of disbandment of HQ OFC were issued. These, however were countermanded in Apr 1990, and the HQ OFC was re-designated as HQ 21 Corps in May 1990. Tac HQ 21 Corps moved to Chandimandir by end of May 1990. Where it was tasked to coord rear area security within the western theatre. Rear HQ 21 Corps mov to Bhopal on 15 Jan 1990. Permanent retention of HQ 21 Corps was auth on 29 Oct 1990.