At the start of First World War there were fifty-four yeomanry regiments in the British Army.
Soon after the declaration of war, it was decided to increase the number of these volunteer mounted regiments.
Territorial Force mounted brigades were known by their district name until August 1915, when they became numbered.
[1] For most of their existence the second line regiments and brigades were used as a coastal defence force.
[2] Most of the second line regiments were converted to cyclist battalions in 1916, and never served in a recognised theatre of war.