The incident prompted global outrage when it became public knowledge in November 1969 . The incident increased to some extent domestic opposition to the U.S. involvement in the Vietnam War when the scope of killing and cover-up attempts were exposed . Initially , three U.S. servicemen who had tried to halt the massacre and rescue the hiding civilians were shunned , and even denounced as traitors by several U.S. Congressmen , including Mendel Rivers , Chairman of the House Armed Services Committee . Only after 30 years were they recognized and decorated , one posthumously , by the U.S. Army for shielding non-combatants from harm in a war zone . 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
No Gun Ri massacre
No Gun Ri massacre
My Lai Massacre