Additional context.
At least 347 and up to 504 civilians, almost all women, children, and elderly men, were murdered by U.S. Army soldiers from C Company, 1st Battalion, 20th Infantry Regiment, 11th Brigade and B Company, 4th Battalion, 3rd Infantry Regiment, 11th Brigade of the 23rd (Americal) Division (organized as part of Task Force Barker). Some of the women were gang-raped and their bodies mutilated, and some soldiers mutilated and raped children as young as 12.
https://en.wikipedia.org/wiki/My_Lai_massacre
His initial life sentence having been modified to a term of 20 years and then further reduced to ten, Calley ultimately served three years of house arrest for the murders. Public opinion at the time about Calley was divided.
https://en.wikipedia.org/wiki/William_Calley