The 1st South Western Mounted Brigade was a formation of the Territorial Force of the British Army, organised in 1908. By 1915 its regiments had been posted away so it was broken up; it never saw active service as a brigade. The Headquarters may have formed the HQ for 2/1st Southern Mounted Brigade.
The brigade was mobilised on 4 August 1914 at the outbreak of the First World War. Initially assigned to the Portsmouth Defences in August 1914,[5] the brigade moved to the Forest Row area of Sussex in October 1914.[3] Thereafter, the regiments left the brigade for other formations.
The North Somerset Yeomanry left the brigade in November 1914, joining the 6th Cavalry Brigade in France on 13 November 1914.[8] It remained with the 6th Cavalry Brigade until April 1918 when it was broken up, sending a squadron to reinforce each of the other regiments in the brigade.[9]
It was later brought back together as a corps cavalry regiment. It was converted to infantry and absorbed into 6th (Wiltshire Yeomanry) Battalion, Wiltshire Regiment in September 1917.[11]
It was later brought back together as a corps cavalry regiment. In September 1917 it was converted to infantry and absorbed into the 15th (Hampshire Yeomanry) Battalion, Hampshire Regiment.[13]
^British divisions were converted to the British Indian Army standard whereby brigades only retained one British regiment or battalion and most support units were Indian (artillery excepted).
Becke, Major A.F. (1936). Order of Battle of Divisions Part 2A. The Territorial Force Mounted Divisions and the 1st-Line Territorial Force Divisions (42โ56). London: His Majesty's Stationery Office. ISBN1-871167-12-4.