The 1/5th Battalion was one of the first Territorial Force units selected to reinforce the Regulars of the British Expeditionary Force (BEF) in France. It landed at Le Havre on 5 November 1914, joining 19th Brigade on 19 November. At this time 19th Bde also included 1st Bn Cameronians 19th Brigade was attached to the 6th Division; later it moved to 33rd Division, a 'Kitchener's Army' formation. The 1/6th Battalion landed at Le Havre as part of the 23rd Brigade in the 8th Division in March 1915 for service on the Western Front. It later joined 33rd Division and in 1916 it merged with the 1/5th to form 5th/6th Bn. The 1/7th Battalion and the 1/8th Battalion landed in Gallipoli as part of the 156th Brigade in the 52nd (Lowland) Division in June 1915; after evacuation from Gallipoli in January 1916 the battalions moved to Egypt and served in the Sinai and Palestine Campaign. They sailed to Marseille in April 1918 and served on the Western Front until the end of the war.