This book provides detailed information about how US Army units were organised and operated in America's longest war. Vietnam Special Forces veteran Gordon L Rottman examines the different types of infantry battalions and the units that supported them, their training and organisation down to platoon level. Aspects of the US Army's conventional and unconventional warfare doctrine are also addressed, along with a discussion of how replacements were trained and integrated into units. Among other areas of the US Army's involvement covered are individual and crew-served weapons, artillery, armoured fighting vehicles, transport, logistics, the complex chain of command, and combat operations.