William Laws Calley Jr., the former Army lieutenant convicted of war crimes for leading the My Lai massacre during the Vietnam War, has died at age 80 in Gainesville, Florida. He passed away on April 28, but his death was reported only recently. Calley was the only individual convicted among 25 charged for the massacre, which saw the slaughter of hundreds of unarmed Vietnamese civilians, including women, children, and elderly men, on March 16, 1968. His conviction and subsequent court-martial in 1971 marked a dark chapter in U.S. military history; he was sentenced to life in prison, but his sentence was later commuted by President Richard Nixon, leading to his release after three years of house arrest. Calley lived in obscurity for decades, occasionally resurfacing, such as in 2009 when he publicly apologized for his actions. The massacre, covered up for over a year by the U.S. Army, remains one of the most notorious war crimes in modern American history.