Which US Army officer was convicted for his role in the My Lai Massacre?

The US Army officer convicted for his role in the My Lai Massacre was William Calley. A first lieutenant, Calley commanded the First Platoon of Charlie Company during the March 16, 1968, attack in Sơn Mỹ village, South Vietnam.

A US Army court-martial found Calley guilty in 1971 of the premeditated murder of 22 unarmed South Vietnamese civilians, along with assault involving a child. He was the only person convicted among the 26 soldiers and officers initially charged in connection with the massacre or its cover-up. His original sentence was life imprisonment with hard labor.

The case became highly controversial because Calley claimed he had been following orders from Captain Ernest Medina, who was later acquitted. President Richard Nixon intervened after the verdict, placing Calley under house arrest; his sentence was eventually reduced, and he served about three and a half years under confinement. Seymour Hersh exposed the massacre through reporting, while Hugh Thompson was a helicopter crewman who helped stop further killings.