The 5th Battalion, King's Own Yorkshire Light Infantry (5th Bn KOYLI), was a unit of Britain's Territorial Force formed in 1908 from Volunteer units originally raised in the West Riding of Yorkshire in 1860. It served in some of the bitterest fighting on the Western Front during World War I, leading the attack at the tank battle of Cambrai and defending Bucquoy in March 1918. In the late 1930s, the battalion was converted to air defence in which role it served during World War II in the Battle of France and the Dunkirk evacuation, in North Africa including the Second Battle of El Alamein, and in the Allied invasions of Sicily and Italy, including service in the rebellion in Greece. Postwar, its successor units served in Anti-Aircraft Command until 1955.