James Louis Moulton was born on 3 June 1906, the son of J. D. Moulton. He was educated at Queen Elizabeth's Grammar School, Barnet, and Sutton Valence School. He married Barbara Aline Coode in 1937, with whom he had one son and one daughter.

He joined the Royal Marines, 1924, and served on HMS Rodney, 1927-9, and HMS Revenge, 1929-30. He volunteered for the Fleet Air Arm and served in 460 and 462 Flights in the aircraft carrier HMS Glorious in the Mediterranean, 1931, and in 824 and 825 Squadrons in HMS Eagle on the China Station, 1933-5. He returned to general service and was sent to Alexandria, during the Abyssinian crisis, with a Royal Marine anti-aircraft battery, 1935.

He attended Staff College, Camberley, 1938. He was appointed GSO3 in the operations section of the British Expeditionary Force, 1939, and was involved in the evacuation at Dunkirk, 1940. He was appointed GSO1 of Force 121, 1942, and took part in Operation Ironclad, the assault on Diego Suarez and occupation of the island of Madagascar. He formed 48 Commando and commanded them during D-Day and the campaign in northern France and Belgium, 1944. He took command of 4 Commando in Germany, 1945, and was mentioned in despatches.

After the war, he directed the Small Arms School, Browndown, and the Commando School, Bickleigh, 1947-9, where he pioneered marine training in mountain and Arctic warfare. He served on the staff of the Commandant General, Royal Marines, 1949-52. He commanded 3 Commando based in Malta, 1952-4. He was promoted Major-General and took charge of Portsmouth Group Royal Marines, 1954-7, initiating the use of helicopters for troop landings. He was Chief of Amphibious Warfare, 1957-61.

He retired from the Army in 1961. He wrote a number of books and was naval editor, 1964-9, and editor, 1969-73, of "Brassey's Annual". He was Colonel Commandant of the Royal Marines, 1969-72.

He was awarded the DSO, 1944, the OBE, 1950, and the CB, 1956.

He died on 22 November 1993.

His publications include: "Haste to the Battle" (1963); "Defence in a Changing World" (1964); "The Norwegian Campaign of 1940" (1966); "British Maritime Strategy in the 1970s" (1969); "The Royal Marines" (1972); and "The Battle for Antwerp" (1978).