The Winter Soldier Investigation, organized by the Vietnam Veterans Against the War to publicize alleged war crimes and atrocities by Americans and allies in Vietnam, begins in Detroit.

The "Winter Soldier Investigation" was a media event sponsored by the Vietnam Veterans Against the War (VVAW) from January 31, 1971, to February 2, 1971. It was intended to publicize war crimes and atrocities by the United States Armed Forces and their allies in the Vietnam War. The VVAW challenged the morality and conduct of the war by showing the direct relationship between military policies and war crimes in Vietnam. The three-day gathering of 109 veterans and 16 civilians took place in Detroit, Michigan. Discharged servicemen from each branch of the armed forces, as well as civilian contractors, medical personnel and academics, all gave testimony about war crimes they had committed or witnessed during the years 1963–1970.

Vietnam Veterans Against the War (VVAW) is an American non-profit organization and corporation founded in 1967 to oppose the United States policy and participation in the Vietnam War. VVAW is a national veterans' organization that campaigns for peace, justice, and the rights of all United States military veterans. It publishes a twice-yearly newsletter, The Veteran; this was earlier published more frequently as 1st Casualty (1971–1972) and then as Winter Soldier (1973–1975).

A war crime is a violation of the laws of war that gives rise to individual criminal responsibility for actions by combatants in action, such as intentionally killing civilians or intentionally killing prisoners of war, torture, taking hostages, unnecessarily destroying civilian property, deception by perfidy, wartime sexual violence, pillaging, and for any individual that is part of the command structure who orders any attempt to committing mass killings, the granting of no quarter despite surrender, the conscription of children in the military, and flouting the legal distinctions of proportionality and military necessity.