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.

Commanding Generals

 * Major General E. Alderson (5 August to 28 September 1914)
 * Lieutenant General Robert George Broadwood (September 1914 to November 1916)

Eastern Mounted Brigade

 * 1/1st Duke of Yorks Own Loyal Suffolk Hussars
 * 1/1st Norfolk Yeomanry
 * 1/1st Essex Yeomanry
 * Essex Battery Royal Horse Artillery

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

 * 1/1st Warwickshire Yeomanry
 * 1/1st Royal Gloucestershire Hussars
 * 1/1st Queen's Own Worcestershire Hussars
 * Warwickshire Battery Royal Horse Artillery

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

 * 1/1st Berkshire Yeomanry
 * 1/1st Royal Buckinghamshire Hussars
 * 1/1st Queen's Own Oxfordshire Hussars
 * Berkshire Battery Royal Horse Artillery

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

 * 1/1st Sherwood Rangers Yeomanry
 * 1/1st South Nottinghamshire Hussars
 * 1/1st Derbyshire Yeomanry
 * 1/1st Nottinghamshire RHA

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

 * 1/1st Pembroke Yeomanry
 * 1/1st Montgomeryshire Yeomanry
 * 1/1st Glamorgan Yeomanry
 * Glamorgan Battery Royal Horse Artillery

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

 * 1/1st Shropshire Yeomanry
 * 1/1st Cheshire Yeomanry
 * 1/1st Denbighshire Hussars
 * Shropshire Battery Royal Horse Artillery

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

 * 1/1st Staffordshire Yeomanry
 * 1/1st Lincolnshire Yeomanry
 * 1/1st Welsh Horse (joined and left early 1915)
 * 1/1st East Riding Yeomanry (joined May 1915)
 * Leicestershire Battery Royal Horse Artillery

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

 * 2/1st Duke of Yorks Own Loyal Suffolk Hussars
 * 2/1st Norfolk Yeomanry
 * 2/1st Essex Yeomanry

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

 * 2/1st Pembroke Yeomanry
 * 2/1st Montgomeryshire Yeomanry
 * 2/1st Glamorgan Yeomanry

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

 * 2/1st Staffordshire Yeomanry
 * 2/1st Leicestershire Yeomanry
 * 2/1st Lincolnshire Yeomanry

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

 * 2/1st Shropshire Yeomanry
 * 2/1st Cheshire Yeomanry
 * 2/1st Denbighshire Hussars

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

 * 2/1st Fife and Forfar Yeomanry
 * 2/1st Lovat Scouts
 * 2/2nd Lovat Scouts

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

 * 2/1st Royal 1st Devon Yeomanry
 * 2/1st Royal North Devon Yeomanry
 * 2/1st West Somerset Yeomanry

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.

Cyclist Units

 * 1/6th (Cyclist) Battalion, the Norfolk Regiment
 * 1/6th (Cyclist) Battalion, the Suffolk Regiment
 * 1/6th (Cyclist) Battalion, the Royal Sussex Regiment
 * 1/25th (County of London) Cyclist Battalion, the London Regiment (left and moved to India in January 1916)
 * 2/25th (County of London) Cyclist Battalion, the London Regiment (joined by November 1915)