This history traces the development of helicopters in the Marine Corps from 1962 to 1973 and is the second in a series of two volumes which between them cover the story of Marines and helicopters from 1946 to 1973. In the period covered by this volume, the Marines at last acquired helicopters fully capable of carrying out an amphibious vertical assault, and they further elaborated their helicopter doctrines and tactics. In the Vietnam war, pilots and machines met and surmounted the test of actual combat. The documentary basis for this monograph was primarily the official records of the Marine Corps and Navy Department, but considerable use was made of interviews and correspondence with key individuals involved in all phases of helicopter development.