The My Lai massacre reportedly ended only after Warrant Officer Hugh Thompson, an Army helicopter pilot on a reconnaissance mission, landed his aircraft between the soldiers and the retreating villagers and threatened to open fire if they continued their attacks. Knowing news of the massacre would cause a scandal, officers higher up in command of Charlie Company and the 11th Brigade immediately made efforts to downplay the bloodshed. The coverup continued until Ron Ridenhour, a soldier in the 11th Brigade who had heard reports of the massacre but had not participated, began a campaign to bring the events to light. After writing letters to President Richard Nixon, the Pentagon, State Department, Joint Chiefs of Staff and several congressmen, with no response, Ridenhour finally gave an interview to the investigative journalist Seymour Hersh, who broke the story in November 1969.

Amid the international uproar that followed Ridenhour’s revelations, the U.S. Army ordered a special investigation into the My Lai massacre and subsequent efforts to cover it up. The inquiry, headed by Lieutenant General William Peers, released its report in March 1970 and recommended that no fewer than 28 officers be charged for their involvement in covering up the massacre. The Army would later charge only 14, including Calley, Captain Ernest Medina and Colonel Oran Henderson, with crimes related to the events at My Lai; all were acquitted except for Calley, who was found guilty of premeditated murder for ordering the shootings, despite his contention that he was only following orders from his commanding officer, Captain Medina. In March 1971, Calley was given a life sentence for his role in directing the killings at My Lai. Many saw Calley as a scapegoat, and his sentence was reduced upon appeal to 20 years and later to 10; he was paroled in 1974.