Which 1968 event saw US soldiers kill hundreds of unarmed villagers in Quang Ngai province?

The 1968 event in which U.S. soldiers killed hundreds of unarmed villagers in Quảng Ngãi province was the My Lai Massacre. It took place on March 16, 1968, in the hamlets of Mỹ Lai 4 and Mỹ Khê 4, part of Sơn Mỹ village in South Vietnam.

American troops entered the area expecting to find Viet Cong fighters, but encountered mostly civilians. Soldiers from Charlie Company, 1st Battalion, 20th Infantry Regiment, 23rd Infantry Division killed large numbers of women, children, and elderly men. The U.S. Army officially counted 347 deaths in Mỹ Lai, while Vietnamese investigations put the total for the wider Sơn Mỹ killings at 504.

The massacre was initially concealed by false reports claiming that enemy combatants had been killed in a battle. Accounts and photographs later made the incident internationally known. Army helicopter crew members Hugh Thompson Jr., Lawrence Colburn, and Glenn Andreotta intervened to protect civilians. Lieutenant William Calley was the only soldier convicted, though his sentence was later reduced.