The 3rd Border Regiment was a reserve battalion previously known, prior to the Childers Reforms, as the Royal Cumberland Regiment of Militia. Throughout the First World War the 3rd Border Regiment remained in the UK as a depot and draft-finding unit specifically involved in the training of recruits. At the outbreak of war in August 1914 they were based in Carlisle but moved to Shoeburyness on mobilisation and then in January 1916 to Conway. In November 1916 it moved to Barrow and finally in March 1917 to Great Crosby for duty with the Mersey Garrison.
Mersey Garrison included:
- 3rd (Reserve) Bn South Wales Borderers. Jun 1915 - 11 Nov 1918
- 3rd (Reserve) Bn Border Regiment. 4 Aug 1914 - 11 Nov 1918
The battalion effectively trained, and subsequently sent overseas, no fewer than 600 officers and 47,000 other ranks.
The 3rd Battalion World War One casualty list has been compiled using the publication Soldiers Died in the Great War 1914-19, Volume 39, The Border Regiment and cross-referenced with the Commonwealth War Graves Commission database. The number of casualties compiled to date does not necessarily reflect the total number of casualties for this battalion due to the possibility of missed names and the (current) exclusion of officers and other ranks that were attached to the Border Regiment. This listing is a work-in-progress.
For the 3rd Battalion roll of honour, see 3rd Battalion Border Regiment Casualty List.
- Specific date of official disbandment not known.