One of the best Osprey books, this one summarizes the short history of the U.S. Marine Corps Raiders in World War II.
While Colonel Darby was forming the army Rangers for the North African and European theatres of operation, Merrit Edson and Evans Carlson were tarining similar commando-units of Marines for the Pacific campaigns.
Merrit Edson was a former Marine Corps aviator, a veteran of counter-insurgency operations in Central America, a staunch advocate of Marine Corps rifle-marksmanship, and a primary developer of the amphibious-warfare concept. He and his Raiders would find their ultimate defining moment defending a vital piece of terrain on Guadalcanal from a massive Japanese assault.
Evans Carlson had been an army-officer in World War I. He resigned his commission, and joined the Marines as an enlisted man. He was re-commissioned as a Marine Corps officer. Most notoriously, he briefly resigned his Marine commission to serve with Mao Tze Tung's communist rebels in China, and learned much about guerilla-warfare in the process. Resuming his place in the Marines, he applied his new knowledge to the Pacific war, especially the raid on Makin Island.
Certain elements were highly opposed to the commando-concept in the Marine Corps, not realizing that special-operations would grow in prominence in the coming decades. It was Evans Carlson's connections with the Roosevelt family, (Franklin Roosevelt's son was a U.S.M.C. officer) that certainly helped the Raiders come into being. Their operatinal history was short, but their exploits were legendary!