On March 16, 1968, U.S. Army troops killed between 300 and 500 civilians in the My Lai hamlet, part of the larger village of Son My, Vietnam. Unfortunately, the My Lai Massacre became one of the most significant symbols of U.S. involvement in the Vietnam War.
 
American soldiers claimed to be acting on orders from their commanding officers. Only one man, Second Lieutenant William Calley, a platoon leader, was convicted for the crimes at My Lai. He served three years of a life sentence before being paroled. 
 
The My Lai Massacre, the Army’s initial concealment of the event, and the failure to hold any high-ranking officers accountable appalled both military and civilian critics. Many drew attention to the Nuremberg Trials, where following orders was rejected as a defense for committing war crimes. Evidence of the My Lai Massacre emerged in late 1969. Calley was sentenced in 1971 and paroled in 1974. The U.S. withdrew from Vietnam in 1975.
accountable
Adjective

responsible or answerable for something.

appall
Verb

to horrify, shock, or disgust.

civilian
Noun

person who is not in the military.

conceal
Verb

to hide.

convict
Verb

to find someone guilty of an illegal act.

crime
Noun

unlawful activity.

evidence
Noun

data that can be measured, observed, examined, and analyzed to support a conclusion.

hamlet
Noun

very small village.

initial
Adjective

first.

massacre
Noun

mass killing of large number of people.

military
Noun

armed forces.

parole
Verb

to conditionally release an inmate from prison prior to the end of their sentence.

platoon
Noun

small military unit usually commanded by a lieutenant.

significant
Adjective

important or impressive.

symbol
Noun

something used to represent something else.

troop
Noun

a soldier.

Noun

small human settlement usually found in a rural setting.

war crime
Noun

severe acts of violence, violating international law, committed against civilians, enemies, prisoners of war, or others during an armed conflict.