This concluding fourth volume in the Official History of the Mesopotamian campaign takes the story from May 1917 to the conclusion of hostilities and the armistice with Turkey, which came into force on 31 October 1918. It begins with a very useful chronological summary of the campaign in Mesopotamia, showing the respective periods and details of operations covered by each of the four volumes which constitute the history of the campaign. An extensive appendix gives details of the distribution of the troops of the Mesopotamia Expeditionary Force as on 27 May 1917 and, in the following appendix, compares the order of battle of the Turkish Sixth Army and its strength in rifles, sabres and machine guns on 17 August 1917. The narrative opens with the description of the River Euphrates operations and the British victory at Ramadi under General Maude, who tragically died of cholera on 18 November 1917. A very able commander, he was a great loss. Other operations described include NW Persia and the Dunsterville Force; in Kurdistan and on the shores of the Caspian Sea (occupation and defence of Baku); and the advance on Mosul. Only one British division, the 13th (Western), served in Mesopotamia compared with nine Indian divisions (including one cavalry). Total casualties amounted to 92,501, of whom 14,814 were killed in action or died of wounds while 12,807 died of disease. Appendices also give the distribution of the Mesopotamia Expeditionary Force on various dates and list the principal officers (brigadier-generals and above) in the Force on 1 December 1917 and 1 November 1918. There is a good index.