The Somerset Light Infantry (Prince Albert's) was a light infantry regiment of the British Army, which served under various titles from 1685 to 1959. In 1959, the regiment was amalgamated with the Duke of Cornwall's Light Infantry to form the Somerset and Cornwall Light Infantry which was again amalgamated, in 1968, with the King's Own Yorkshire Light Infantry, the King's Shropshire Light Infantry and the Durham Light Infantry to form The Light Infantry. In 2007, however, The Light Infantry was amalgamated further with the Devonshire and Dorset Regiment, the Royal Gloucestershire, Berkshire and Wiltshire Regiment and the Royal Green Jackets to form The Rifles.

The regiment also had four Territorial battalions, although only two would serve overseas. Throughout the war the 4th Battalion, Somerset Light Infantry was serving with the 129th Brigade, alongside the 4th and 5th Wiltshire Regiment, part of the 43rd (Wessex) Infantry Division, and spent most of its existence in the United Kingdom in Kent under XII Corps of Southern Command.

The 7th Battalion, which had been created on 24 August 1939 as a 2nd Line duplicate of the 5th, was originally serving alongside both the 5th and 6th battalions in 135th Brigade, of the 45th Division. On 11 September 1942 the battalion was transferred to the 214th Infantry Brigade, which included the 5th Duke of Cornwall's Light Infantry and the 9th Somersets (later replaced by the 1st Worcestershire Regiment).

Both the 4th and 7th battalions served in the North West Europe Campaign after the Normandy landings on 6 June 1944, D-Day. The division fought very well in the Battle of Normandy, particularly so during the Battle for Caen in Operation Epsom in late June, at the Battle for Hill 112 (Operation Jupiter). During the battle "the 4th Somersets, out of a strength of 845, suffered 556 casualties, and between 26 June and 14 July 4th SLI received 19 reinforcement officers and 479 ORs as replacements.The battalion became involved in trench warfare similar to that of the Great War. They later played a large part in the disastrous Operation Market Garden. They later played a small role in the Battle of the Bulge and finally took part in Operation Plunder, the crossing of the River Rhine by the Allies.