FIFTY years ago this week, on March 16, 1968, around 200 US soldiers from Charlie and Bravo companies burst into a Communist-dominated area in South Vietnam known to GIs as “Pinkville”. In less than four hours, more than 500 Vietnamese civilians — including elderly men, women and children — were dead in the villages of My Lai 4, Binh Tay, Binh Dong and My Khe 4.

The American forces sustained one casualty that day; it was self-inflicted. Thirteen soldiers faced allegations of rape, but those cases were dismissed for lack of evidence. Thirty soldiers were accused of murder — but were never prosecuted. Only Second Lt William L Calley, leader of Charlie Company’s first platoon in My Lai 4, would be convicted of murder and sentenced to life in prison. Calley appealed the verdict and was later paroled in Nov 1974.

Historians have long acknowledged the significance of the My Lai massacre. Thomas E Ricks argues that it marked “the low point of the 20th-century United States military”. Max Hastings called it “the most notorious war crime of the Vietnam era”.

How well have we learned its lessons? In 1970, the Pentagon launched a top-secret investigation (it was declassified in 1994) into numerous allegations of atrocities in Vietnam and concluded that more than 300 massacres had occurred — with My Lai the worst. No other crime, Gen William Westmoreland wrote in his 1976 memoir, “even remotely approached the magnitude and horror of My Lai”.

What happened at My Lai lays bare the type of war fought by Americans in Vietnam: one of attrition based on body counts, “search-and-destroy missions” and “free-fire zones” — euphemisms for blanket killings that often included non-combatants.

My Lai underscores the greatest difficulty facing US forces on the ground: how to distinguish between the enemy and the innocent. The fundamental reality to US soldiers was that all Viet Cong were Vietnamese, yet not all Vietnamese were Viet Cong. How to resolve this problem? Kill every Vietnamese, even the children, Calley asserted in his 1971 memoir. Otherwise, he said, mothers of sons killed years later in the long war would yell at him, “Why didn’t you kill those babies that day?”

The facts of My Lai force us to look at what the soldiers faced. Consider a 19-year-old who had never been outside the United States, knew little or nothing about Vietnam and had no real sense of why he was there. What should we expect him to do when, scared to death, he entered a Vietnamese village known as an enemy hot spot in which all its inhabitants wore peasant garb — whether they were non-combatants, Viet Cong sympathisers, or themselves Viet Cong?

Notably, Charlie Company had lost 28 soldiers during the recent Tet Offensive to land mines, booby traps and snipers. Numerous soldiers reported that, in the briefing the day before the My Lai operation, Capt Ernest Medina told his three platoons they had a chance for revenge: the civilians would have departed for Quang Ngai City on that market day, and Army intelligence reported that more than 200 forces from the Viet Cong’s 48th Local Force Battalion lay embedded at My Lai 4. When US troops began their assault, they expected to encounter only the enemy. And they were driven by fear, frustration, vengeance, racial hatred and the determination to shoot first as the chief means to survive against a force twice their size.

As it turned out, Army intelligence was wrong: no Viet Cong were in the villages. Every victim of the massacre was a civilian.

In the midst of this carnage appeared a glimmer of human decency and courage. Warrant Officer Hugh Thompson, accompanied in his small observation helicopter by 20-year-old crew chief Glenn Andreotta and 18-year-old gunner Lawrence Colburn, intervened to stop the killings and reported them to the command base, bringing about a ceasefire before noon that doubtless saved numerous Vietnamese lives.

After My Lai, the Army sought to restore its image by developing a volunteer force based on personal character, along with improved discipline and training, and led by officers who were taught combat ethics and the importance of enforcing the principle of restraint underlying the rules of land warfare, particularly in heavily populated areas. But the graphic abuses committed by US forces decades later at Abu Ghraib prison during the war in Iraq, along with the CIA’s torture of detainees, raise the question of whether any reform, no matter how effective, can ever fully eliminate the danger.

In terms of history, the significance of My Lai remains unambiguous. The massacre and its aftermath intensified a growing public call to end the war in Vietnam — and not only by anti-war groups. Calley’s conviction and sentence led supporters of the war to insist that if their soldiers were not allowed the freedom to kill the enemy, they must pull out of Vietnam.

But My Lai transcends history. Its lessons are universal. Historian Roger Spiller declared that “the most frightening lesson” he has learned from military history is that “ordinary” people are capable of heinous crimes in the right circumstances. The key to ending atrocities in war is as obvious as it has been unattainable: end war or accept Spiller’s conclusion that “we are all one step away from My Lai”.

The writer is University Research Professor of History Emeritus, University of Alabama, and the author of My Lai: Vietnam, 1968, and the Descent Into Darkness.

—By arrangement with The Washington Post

Published in Dawn, March 18th, 2018