1/1st
August 1914 : in Exeter. Part of the 2nd South Western Mounted Brigade
October 1915 : dismounted, moved to Gallipoli. Returned to Egypt in 30 December 1915.
February 1916 : Brigade was absorbed into 2nd Dismounted Brigade.
4 January 1917: together with the 1/1st North Devon Yeomanry, formed the 16th Bn, (Royal 1st Devon and North Devon Yeomanry), the Devonshire Regiment. This unit formed part of 229th Brigade, 74th (Yeomanry) Division TF. On 7 May 1918, the Bn landed at Marseilles and proceed to the Western Front, where it then remained.
2/1st
Formed September 1914, and remained in UK until in November 1916, converted into a Cyclist unit and redesignated 4th Yeomanry Cyclist Regiment. Resumed original identity in March 1917. Moved to Ireland in May 1918.
3/1st
Formed in 1915. Remained in United Kingdom until disbanded in early 1917.