The only Irish unit involved in the campaign in Mesopotamia was
1st Bttn, Connaught Rangers, Ferozepore Brgade, 3rd (Lahore) Division, which formed part of the Indian Corps.
The Corps had previously fought on the Western Front in late 1914 and during the spring of 1915, before they were withdrawn and sent to the Middle East in the middle of 1915.
Arriving in Basra in January 1916, the Rangers joined up with 9th Infantry Brigade, which were attached to 7th Division, in the attempt to relieve 6th Indian Division at Kut, and the Brigade were soon involved in bitter fighting with Turkish forces at Hanneh and this continued into April 1916.
After several months of besiegement in Kut, General Townshend's garrison of over 9,000 British and Indian troops eventually surrendered in April 1916
After Kut and Baghdad were both recaptured within the next 12 months, 1st Bttn, Connaught Rangers stayed in Mesopotamia until April 1918 when they moved to Palestine/Transjordan to take part in offensive activity against Turkish forces and where they ended their war.