Arrived in Mesopotamia to take command of British forces in March 1915. Remained at his headquarters in Basra and did not visit front-line conditions. After early cheap successes, became supremely optimistic that the small force under his command could capture Baghdad. Must be held at least partially responsible for a continuing failure to supply the force with equipment, transport and basic necessities, and for an abject failure to provide medical support for the fighting troops.

Invalided back to India due to ill-health 18 January 1916 at a crucial moment as the Tigris Force was moving to relief the garrison at Kut-al-Amara.