The Battle of Ấp Bắc was a major battle fought on 2 January 1963 during the Vietnam War, in Định Tường Province, South Vietnam. On 28 December 1962, US intelligence detected the presence of a radio transmitter along with a sizable force of Viet Cong (VC) soldiers, reported to number around 120, in the hamlet of Ap Tan Thoi in Dinh Tuong Province, home of the Army of the Republic of South Vietnam (ARVN) 7th Infantry Division. The South Vietnamese and their US advisers planned to attack Ap Tan Thoi from three directions to destroy the VC force by using two provincial Civil Guard battalions and elements of the 11th Infantry Regiment, ARVN 7th Infantry Division. The infantry units would be supported by artillery, M113 armored personnel carriers (APCs), and helicopters. However Viet Cong forces anticipated a major attack from the South Vietnamese government from a variety of sources, including movement of supplies, an undercover VC agent and decoded radio communications from the ARVN. Accordingly the VC prepared for an attack by US and South Vietnamese forces.

The Vietnam War was a conflict in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. It was the second of the Indochina Wars and was a major conflict of the Cold War. While the war was officially fought between North Vietnam and South Vietnam, the north was supported by the Soviet Union, China, and other communist states, while the south was supported by the United States and other anti-communist allies, making the war a proxy war between the United States and the Soviet Union. It lasted almost 20 years, with direct U.S. military involvement ending in 1973. The conflict also spilled over into neighboring states, exacerbating the Laotian Civil War and the Cambodian Civil War, which ended with all three countries officially becoming communist states by 1976.