It served in the Mesopotamian Campaign on the Euphrates Front throughout its existence.

[1] The 42nd Indian Brigade was formed in April 1916 and, on arrival in Mesopotamia, joined the 15th Indian Division when it was formed on 7 May 1916.

The brigade remained with the division on the Euphrates Front until the end of the war.

It took part in the action of As Sahilan (11 September 1916), the Capture of Ramadi (28 and 29 September 1917), the Occupation of Hīt (9 March 1918) and the action of Khan Baghdadi (26 and 27 March 1918).

[2] At the end of the war, the division was rapidly run down and it (along with the brigade) was disbanded in March 1919.