I'll try. In Vietnam there were "free fire zones", areas where everyone was regarded as a hostile and it was OK to shoot anything that moved, including people.

Calley was given to think that he was in a free fire zone, that everyone in that village was a hostile, and that it was OK to kill them. He was ordered to kill the livestock and burn down the houses.

Calley rounded up a group of people in the center of a village and ordered them shot. He also shot them. More groups were rounded up and Calley participated in their massacre.

Calley in my opinion had the duty to disobey the order given by his company captain, to kill all all VC, VC being identified as all villagers.

One can understand the bind Calley was in. He was a weak person seeking the approval of his superiors AND he had a duty to disobey that order.

That he didn't, that he slaughtered hundreds of civilians, earned him the death penalty. As should Captain Ernest Medina, his immediate superior.

As, possibly, should have people under Calley. In my opinion.

Also, was he used by the others? Did they pin the blame on him? They sure did. And the rest of them got away free.