The 4th Special Service Brigade was a brigade-sized formation of the British Commandos formed during the Second World War in March 1944 from battalion-sized units of the Royal Marines. Due to the success of the British Army Commandos' operations in Norway, the Channel Islands, St. Nazaire, and the Middle East, the Admiralty dissolved the Royal Marines Division in late 1942 and reorganized its amphibious assault infantry into eight additional Commando units.