1st Mounted Division The 1st Mounted Division was formed in August 1914 for the home defence of the United Kingdom . It was formed from existing mounted brigades of the Territorial Force , each of three regiments of Yeomanry . The Divisional order of battle would often change , as the First Line Brigades left for service overseas and were then replaced by Second Line units . It would be converted to the 1st Cyclist Division in July 1916 , and was then broken up in November 1916 without being involved in active service . An unrelated 1st Mounted Division was formed in July 1916 , from the 3rd Mounted Division , lasting until September 1917 . Another incarnation of 1st Mounted Division was created in April 1918 from the Yeomanry Mounted Division , lasting until July 1918 . Order of battle . Eastern Mounted Brigade . In September 1915 , the brigade was dismounted and moved via Egypt to ANZAC bridgehead on Gallipoli , attached to 54th Division . 1st South Midland Mounted Brigade . The Brigade moved to the 2nd Mounted Division in September 1914 , and was replaced in the Division by the South Wales Mounted Brigade . 2nd South Midland Mounted Brigade . The Brigade moved to the 2nd Mounted Division in September 1914 and was replaced in the Division by the Welsh Border Mounted Brigade . Nottinghamshire and Derbyshire Mounted Brigade . The Brigade moved to the 2nd Mounted Division in August 1914 and was replaced in the Division by the North Midland Mounted Brigade . South Wales Mounted Brigade . The Brigade joined the Division in September 1914 to replace the 1st South Midland Mounted Brigade and was itself replaced in the Division by the 2 / 1st Eastern Mounted Brigade . In November 1915 the Brigade units were dismounted and moved to Egypt in March 1916 , and was absorbed along with the Welsh Border Mounted Brigade into 4th Dismounted Brigade which joined the Western Frontier Force . The would be re designated as the 231st Brigade , 74th ( Yeomanry ) Division . Welsh Border Mounted Brigade . The Brigade joined the Division in September 1914 to replace the 2nd South Midland Mounted Brigade , in November 1915 the regiments were dismounted and moved to Egypt in March 1916 , and was absorbed into 4th Dismounted Brigade along with the South Wales Mounted Brigade . North Midland Mounted Brigade . The Brigade joined the Division in September 1914 , to replace the Nottinghamshire and Derbyshire Mounted Brigade . In October 1915 , the Brigade left and became an independent command and would be replaced in the Division by the 2 / 1st North Midland Mounted Brigade . The orders to move to Salonika were altered and the Brigade moved to Egypt instead , arriving November 1915 . They were then redesignated the 22nd Mounted Brigade in April 1916 . 2 / 1st Eastern Mounted Brigade . The Brigade joined Division in March 1916 , to replace the South Wales Mounted Brigade . They left the Division by July 1916 . 2 / 1st South Wales Mounted Brigade . The Brigade replaced the Eastern Mounted Brigade in October 1915 . They were then redesignated the 4th Mounted Brigade in July 1916 . In the same month when this Division became the 1st Cyclist Division , they were then redesignated as the 4th Cyclist Brigade . The Brigade was broken up in November 1916 . 2 / 1st North Midland Mounted Brigade . The 2 / 1st North Midland Mounted Brigade Replaced the North Midland Mounted Brigade in October 1915 . It was redesignated as the 3rd Mounted Brigade in July 1916 . In the same month when this Division became the 1st Cyclist Division , they were then redesignated as the 3rd Cyclist Brigade . The Brigade was broken up in November 1916 . 2 / 1st Welsh Border Mounted Brigade . The brigade joined the Division in March 1915 to replace the Welsh Border Mounted Brigade , they would leave the Division in July 1916 and were replaced by the 2nd Mounted Brigade . 1st Mounted Brigade . The brigade which was redesignated from the 2 / 1st Highland Mounted Brigade , joined the Division in May 1916 to replace the 2 / 1st Eastern Mounted Brigade , they would leave the Division in July 1916 . 2nd Mounted Brigade . The brigade which was redesignated from the 2 / 2nd South Western Mounted Brigade , joined the Division in May 1916 to replace the 2 / 1st Welsh Border Mounted Brigade . In July 1916 when this Division became the 1st Cyclist Division , they would be redesignated as 1st Cyclist Brigade . The Brigade was broken up in November 1916 .