March 16, 1968 – My Lai Massacre

From Wikipedia:

Soldiers went berserk, gunning down unarmed men, women, children and babies. Families which huddled together for safety in huts or bunkers were shown no mercy. Those who emerged with hands held high were murdered. … Elsewhere in the village, other atrocities were in progress. Women were gang raped; Vietnamese who had bowed to greet the Americans were beaten with fists and tortured, clubbed with rifle butts and stabbed with bayonets. Some victims were mutilated with the signature “C Company” carved into the chest. By late morning word had got back to higher authorities and a cease-fire was ordered. My Lai was in a state of carnage. Bodies were strewn through the village.