
The My Lai massacre (Vietnamese: Thảm sát Mỹ Lai) was a war crime committed by United States Army personnel on 16 March 1968, involving the mass murder of unarmed civilians in Sơn Tịnh district, South Vietnam, during the Vietnam War. Between 347 and 504 civilians were killed by U.S. soldiers from Company C, 1st Battalion, 20th Infantry Regiment and Company B, 4th Battalion, 3rd Infantry Regiment, 11th Brigade, 23rd (Americal) Infantry Division. Victims included men, women, children, and infants. Some of the women were gang-raped and their bodies mutilated, and some soldiers mutilated and raped children who were as young as 12. It is the largest publicized massacre of civilians by U.S. forces in the 20th century.
Twenty-six soldiers were charged with criminal offenses, but only Lieutenant William Calley Jr., a platoon leader in C Company, was convicted. Found guilty of murdering 22 villagers, he was originally given a life sentence but served three-and-a-half years under house arrest after U.S. president Richard Nixon commuted his sentence.
The massacre, which was later called "the most shocking episode of the Vietnam War", took place in two hamlets of Sơn Mỹ village in Quảng Ngãi Province. These hamlets were marked on the U.S. Army topographic maps as My Lai and My Khe. The U.S. Army slang name for the hamlets and sub-hamlets in that area was Pinkville, and the carnage was initially referred to as the Pinkville Massacre. Later, when the Army started its investigation, the media changed it to the Massacre at Songmy. Currently, the event is referred to as the My Lai Massacre in the U.S. and called the Sơn Mỹ Massacre in present-day Vietnam.
The massacre prompted global outrage when it became public knowledge in November 1969. It contributed to domestic opposition to the U.S. involvement in the Vietnam War, both because of the scope of killing and attempts to cover up the events.
Initially, three U.S. servicemen who had tried to halt the massacre and rescue hiding civilians were shunned, and even denounced as traitors by several U.S. congressmen, including Mendel Rivers (D–SC), Chairman of the House Armed Services Committee. Thirty years later, these servicemen were recognized and decorated, one posthumously, by the U.S. Army for shielding non-combatants from harm in a war zone.