The regiment was formed on the creation of the Territorial Force in April 1908 and placed under orders of the Lowland Mounted Brigade. It was headquartered Edinburgh (one source says at 18 Dundonald Street, another gives Wemyss Place) with the squadrons being headquartered as follows:
A Squadron: Dunbar (and drill stations at Earlston, Greenlaw, North Berwick, Musselburgh, Lauder, Kelso, Berwick, Haddington, Tranent, East Linton, Duns and Coldstream)
B Squadron: Edinburgh (Musselburgh, Dalkeith, Penicuik, Gorebridge, Lasswade and Loanhead)
C Squadron: Hawick (Galashiels, Jedburgh, Innerleithen, Kelso, Melrose, Newcastleton, Peebles, Selkirk, Stow, Yetholm and St Boswells)
D Squadron: Edinburgh (Linlithgow, Bathgate, Broxburn, Hopetoun, Mid-Calder, South Queensferry, Ratho and Winchburgh)
1/1st Lothians & Border Horse Yeomanry
- August 1914 : moved with the brigade to Cupar. C Squadron was broken up on mobilisation, with men and horses going to the other squadrons.
- Summer 1915: regiment split up as follows:
- Regiment HQ and B Squadron moved to Aldershot and came under command of 25th Division; landed at Le Havre 27 September 1915; 11 May 1916 left Division and became V Corps Cavalry Regiment (along with two squadrons of Glasgow Yeomanry); July 1917 left the Corps, dismounted and went for infantry training; September 1917 absorbed into 17th Battalion, the Royal Scots
- A Squadron joined 26th Division at Sutton Veny on 30 July 1915; moved to France with division in September 1915 and went on to Salonika in November; on 29 November 1916 left division and came under orders of 8th Mounted Brigade until 14 January 1917; 11 May 1917 became XII Corps Cavalry Regiment with D Sqn (below)
- D Squadron moved to Aldershot and came under orders of 22nd Division; moved to France with division in September 1915 and went on to Salonika in November; from 29 November 1916 as per A Sqn.
2/1st Lothians & Border Horse Yeomanry
- Formed in September 1914 as a “second line” (training, draft-supplying reserve) for the 1/1st. Came under orders of the 2/1st Lowland Mounted Brigade. Moved to Dunbar.
- March 1916: brigade became 20th Mounted Brigade.
- July 1916: converted to a cyclist unit in 13th Cyclist Brigade.
- November 1916: brigade becomes 9th Cyclist Brigade.
- Was at Haddington by July 1917.
- May 1918: moved to Ireland, being at Londonderry and Enniskillen.
3/1st Lothians & Border Horse Yeomanry
- Formed in 1915 as a “third line” (training, draft-supplying reserve for the 1/1st and 2/1st).
- 1916: affiliated to 2nd Reserve Cavalry regiment at Aldershot.
- Early 1917: absorbed into 4th Reserve Cavalry Regiment at Aldershot.
In the 1917 renumbering of the Territorials, the Lothians & Border Horse Yeomanry issued numbers from the block 120001-125000. Corps of Dragoons.
Did you know you can download a complete copy of the history of the regiment? Free of charge, care of archive.org: The war record of 4th Bn, KOSB and Lothians and Border Horse