This monograph describes U.S. Army Riverine planning and operations in the Republic of Vietnam during the years 1966 through 1969. Since the personal experience of the author was with preparations for riverine operations and the initial operations themselves, emphasis has been placed on these activities through early 1968. In summarizing operations conducted in the balance of the three-year period, particular attention has been called to significant trends or changes in riverine operations in Vietnam, a co-operative enterprise of the U.S. Army and the U.S. Navy. Looking back from the vantage point of early 1972, this study attempts to reconstruct the events and describe the situation as it was from 1966 through 1969, using official records, reports, and personal interviews.