The regiment mobilised in August 1914, but remained in England until 1915, when they sailed for Egypt with 2nd Mounted Division. During the move, the horse transport "Wayfarer" was torpedoed on 11 April 1915 having just left Avonmouth; although she did not sink, the horses had to be rescued. Volunteers of the regiment saved 763 horses, receiving a Military Cross and twelve Meritorious Service Medals. They arrived in Egypt on 24 April, before being moved to Gallipoli for service as dismounted infantry. They landed at Suvla Bay on 18 August and saw action at the Battle of Scimitar Hill, on 21 August. The regiment took heavy losses, but remained in the line until withdrawn at the end of October. It was assigned to the Australian Mounted Division in February 1917, serving in Palestine as cavalry, and seeing action at the First and Second Battles of Gaza, the Charge at Huj as well as the Battle of Mughar Ridge and the Battle of Jerusalem. It was withdrawn in April 1918, and amalgamated with the 1/1st South Nottinghamshire Hussars into B Battalion, Machine Gun Corps, soon renamed the 100th (Warwickshire and South Nottinghamshire Yeomanry) Battalion, Machine Gun Corps, which would serve on the Western Front for the remainder of the war. On 27 May 1918 this unit was on board the transport vessel "Leasowe Castle" which was sunk by SM UB-51 with a loss of 101 lives. At the Armistice, it was serving as Army Troops with the Fourth Army.