On the outbreak of the First World War Maud was put in charge of a brigade on the Western Front but was seriously wounded. On recovery he was promoted to commander of the 13th Division and sent to Gallipoli. After suffering 50 per cent losses, Maud and his men were transferred to Mesopotamia in March 1916.
In July 1916 it was decided that Maude should replace General Gorringe of the Indian Army as commander of the frontline Tigris Corps. The following month he was put in charge of al the Anglo-Indian forces in Mesopotamia. After reorganising his forces Maude led a series of effective offensives up the Tigris and in March 1917 successfully captured Baghdad.
While leading the attack on Ramadi Frederick Maude went down with cholera and although he was quickly taken back to Baghdad he died on 18th November 1917. Rumours circulated that he had been poisoned but the evidence suggests that he probably contracted the disease from contaminated milk.