 It mobilised on 4 August 1914 and was stationed at Hatfield Peverel and Stansted until June 1915.On 12 June 1915, it joined the 9th Cavalry Brigade, 1st Cavalry Division in France, eventually dismounting to serve in the Battle of the Somme, Battle of Cambrai and the Hundred Days Offensive in 1918.As such, it was one of only six yeomanry regiments to be posted to a regular cavalry division in the war.