On February 19, 1970, five U.S. Marines entered the South Vietnamese village of Sơn Thắng seeking revenge for an ambush that killed their comrades. Believing the village harbored Viet Cong, they executed sixteen unarmed women and children. The massacre, quickly exposed and investigated, became one of the most shocking war crimes of the Vietnam War - an atrocity that revealed the moral collapse and human cost of the conflict.