The 4th and 5th Battalions of the Wiltshire Regiment were both Territorial Army (TA) units called up to active duty with the start of the Second World War. The 4th Battalion, Wilts had been the original Territorial battalion when the Territorial Army was reorganized during the early 1920s. The 5th Battalion, Wiltshire Regiment was formed on 25 March 1939 as the 2nd Line duplicate of the 4th Battalion as part of the expansion of the Territorials in throughout 1939 when another European conflict seemed increasingly likely. From 1939 to 1944, both units remained in England training, both attached to 129th Infantry Brigade, alongside the 4th Somerset Light Infantry, part of the excellent 43rd (Wessex) Infantry Division. Although the 5th Battalion was a 2nd Line Territorial unit, it was assigned to a 1st Line brigade and division. This was because the 43rd Division and its 2nd Line duplicate, the 45th, was not formed as an exact mirror duplicate as most were, but was instead split on a geographical basis, with all the units from Wiltshire, Hampshire and Dorset being assigned to the 43rd, whereas those from Devonshire, Somerset and Cornwall assigned to the 45th.