On this day in 1968, the My Lai Massacre took place when U.S. troops in the Sơn Tịnh District, South Vietnam massacred and raped hundreds of unarmed civilians, including women, children, and infants. The event was a war crime and suppressed by the U.S. military despite multiple whistleblowers coming forward. Estimates of the total killed range between 347 and 504.

Despite two soldiers writing letters to their superiors about the possibility of a war crime having taken place, the U.S. government claimed that the event was a military victory for several months after it occurred. It was only after an independent journalist broke the story and the true nature of the massacre became public that twenty-six soldiers were charged with criminal offenses.

Only one, Lieutenant William Calley Jr., was convicted. Found guilty of killing 22 villagers, he was originally given a life sentence, but served only three and a half years under house arrest. The incident sparked global outrage and spurred the domestic anti-war movement. Three U.S. servicemen who had tried to halt the massacre and rescue the hiding civilians were shunned and denounced as traitors, including by multiple U.S. Congressmen.

Along with the No Gun Ri massacre in South Korea 18 years earlier, Mỹ Lai was one of the largest publicized massacres of civilians by U.S. forces in the 20th century