The 1st South Western Mounted Brigade was a formation of the Territorial Force of the British Army, organised in 1908.

The Headquarters may have formed the HQ for 2/1st Southern Mounted Brigade.

[3] As the name suggests, the units were drawn from South West England, predominantly Wiltshire, Somerset, Hampshire and Dorset.

[4] 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.