The 51st Indian Brigade started forming in Mesopotamia from August 1917 as part of the 17th Indian Division.

It was formed from battalions that had already been in Mesopotamia for some months, guarding lines of communications.

It remained with the division for the rest of the war, taking part in the action at Fat-ha Gorge on the Little Zab (23–26 October 1918) and the Battle of Sharqat (28–30 October 1918).

[1] At the end of the war, the 17th Division was chosen to form part of the occupation force for Iraq.

In August 1923, the division was reduced to a single brigade; the last British troops left in March 1927 and the Indian ones in November 1928.