3rd Mounted Division

2/2nd Mounted Division 3rd Mounted Division 1st Mounted Division The Cyclist Division
Active	6 March 1915 – June 1919
Country	United Kingdom
Branch	British Army
Type	Yeomanry Bicycle infantry
Size	Division
Service	World War I
Commanders
Notable commanders	John Burn-Murdoch

The 3rd Mounted Division was a Yeomanry Division of the British Army active during World War I. It was formed on 6 March 1915 as the 2/2nd Mounted Division, a replacement/depot formation for the 2nd Mounted Division which was being sent abroad on active service. In March 1916, it was renumbered as the 3rd Mounted Division and in July 1916 as the 1st Mounted Division. In September 1917, the division was reorganized as a cyclist formation and redesignated as The Cyclist Division. It remained in the United Kingdom throughout the war and was disbanded in June 1919.

In accordance with the Territorial and Reserve Forces Act 1907 (7 Edw. 7, c.9) which brought the Territorial Force into being, the TF was intended to be a home defence force for service during wartime and members could not be compelled to serve outside the country. However, on the outbreak of war on 4 August 1914, many members volunteered for Imperial Service. Therefore, TF units were split into 1st Line (liable for overseas service) and 2nd Line (home service for those unable or unwilling to serve overseas) units. 2nd Line units performed the home defence role, although in fact most of these were also posted abroad in due course. Likewise, existing pre-war formations (brigades and divisions) formed duplicate 2nd Lines with the same structure as their 1st Line parents.

On 2 September 1914, the 2nd Mounted Division was formed in and around the Churn area of Berkshire with the 1st South Midland, 2nd South Midland, Nottinghamshire and Derbyshire, and London Mounted Brigades. In November 1914, the division moved to Norfolk on coastal defence duties and in March 1915 the division was put on warning for overseas service.

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