A country can minimize the evil perpetrated in its name, by its soldiers, by going to war only as a last resort; maintaining discipline as best as is humanly possible during armed conflict; holding war criminals responsible for their deeds; and treating those who stop or uncover crimes against humanity as heroes rather than villains. The hero of the My Lai massacre was helicopter pilot Hugh Thompson Jr. Along with the members of his crew, Glenn Andreotta and Lawrence Colburn, he began observing the U.S. troops in Sơn Mỹ Village from the air, believing them to be attacking enemy forces. It took time for him to realize that the soldiers of Company C were committing mass murder. At that moment, he could easily have just flown away.

Instead, he landed his helicopter, confronted heavily armed child killers and rapists amid their killing frenzy, and saved the lives of at least 11 civilians. As The New York Times described it decades later in his obituary:

He touched down near a bunker in which a group of about 10 civilians were being menaced by American troops. Using hand signals, Mr. Thompson persuaded the Vietnamese to come out while ordering his gunner and his crew chief to shoot any American soldiers who opened fire on the civilians. None did. Mr. Thompson radioed for a helicopter gunship to evacuate the group, and then his crew chief, Glenn Andreotta, pulled a boy from a nearby irrigation ditch, and their helicopter flew him to safety.

Upon returning to base he reported what he saw. And that likely saved many more innocents, for commanders ordered a halt to an operation that had been planned to include forays into other nearby hamlets where more killings could have taken place.

When I reflect on the My Lai massacre, I cannot put myself in the minds of the dozens of men who perpetrated it nor the three who risked their lives to intervene. I don’t know if anyone can fully explain either savagery or heroism in war.

But a country needn’t solve any mystery to know how it ought to respond to mass murder. And that’s why, in my judgment, the U.S. should feel the most shame for the fact that just one man, Lieutenant William Calley, was ever punished for the mass killings. Found guilty of murdering no less than 20 people, he was sentenced to life in prison, but put on house arrest instead after President Nixon intervened. In the end, even he served just three-and-a-half years of house arrest. Then he went free.

He is now 74.

And Hugh Thompson? After news of the My Lai massacre reached the United States, this was his experience:

After it broke, I was not a good guy. I was sure not being invited to Annapolis or West Point or any other university that I’ve been to since, because I was a traitor. I was a communist. I was a sympathizer. I was neither one of those, I didn’t think. I was very confused about why I was being treated this way, because how wrong can it be helping a fellow human? And I’m no pacifist either. You know, I’m not one of these peacenik guys. So I was just very confused, and that went on for about 30 years. I became invisible. When it first broke, people thought everybody was picking on Lieutenant Calley. Believe me, Lieutenant Calley was very guilty. There is no way to get around it. But we, being Americans, we cheer for the underdog, so that’s what people were thinking. They thought the establishment was picking on this little guy. The turmoil the United States was in during this time was quite significant. We had demonstrations on every campus in the United States except about three, and I guarantee they were right outside your gate, because we had been there too long. We were [the demonstrators said] nothing but a bunch of baby killers, you know, and it was just a bad time for America. And Congress came after me real hard. A very senior congressman made a public statement that if anybody goes to jail in this My Lai stuff, it will be the helicopter pilot.

He later told 60 Minutes, “I’d received death threats over the phone. Dead animals on your porch, mutilated animals on your porch some mornings when you get up.” He and his crew did not receive the Soldier’s Medal until 1998. He lived to see the Army teach his behavior as a model of good soldiering. He died in 2006.