The 2nd Sussex Rifle Volunteers was a part-time unit of the British Army first raised from the county of Sussex in 1859. It later became the 4th Battalion, Royal Sussex Regiment. A detachment served in the Second Boer War. During the First World War, the battalion fought at Gallipoli, in Sinai and Palestine, and then in the final months of the war on the Western Front. In the Second World War, both the battalion and its duplicate served in the Battle of France and were evacuated from Dunkirk. The 4th Battalion then fought at the Second Battle of El Alamein, and served in the Middle East until the end of the war. It continued in the postwar Territorial Army until it lost its individual identity in a series of mergers from 1967.