This book utilizes select elements of operational art from ADRP 3-0 to examine how General Lewis Walt employed operational art as the III Marine Amphibious Force (III MAF) commander in Vietnam from June 1965-June 1967. This book addresses a significant shortfall in literature focused on Corps-level operational commanders during the Vietnam War. In combat, III MAF faced a hybrid threat of North Vietnamese regular forces and entrenched Viet Cong main force and guerrilla units. Apart from the significant challenges of combat operations, General Walt found himself confronted by vague and restricting U.S. policy, ineffective U.S. and South Vietnamese civilian and governmental agencies, a complex South Vietnamese civilian and military operating environment, and competing warfighting strategies and interservice rivalries between his U.S. Army combat chain-of-command and internal Marine Corps leadership. Despite these challenges, Walt developed and executed an effective operational approach which addressed substantial enemy threats while supporting the government of South Vietnam and its military forces.