Calley was a scapegoat, was not set up. He ordered the shootings and participated. There is evidence he thought that was what his superiors wanted.

Whatever else, it would have been an illegal order, but Calley was not the sort to buck authority. There were many others involved, however, in the massacre and in the cover-up, reaching way up into higher ranks.

Calley, not a strong person, was in an atmosphere which regarded all Vietnamese as hostile, was disdained by fellow officers and his unit was suffering casualties. He did not receive the proper support and guidance from his leaders. As a junior officer he was both a pawn and a king. Feeling impotent and rejected, he did what he could to feel powerful and in control. He taught them.

One's heart can go out to him. He undoubtedly felt he was following orders. The massacre was covered up by people far above him. They should have all been prosecuted, and no one was. Germans were executed for less.

Enlisted people who were shooting were aware it was wrong, but that there was an order. Again, that excuse was not allowed Germans in WWII, who received far more than 3.5 years house arrest.

Calley deserved the firing squad. So did others, above and below him. He was a scapegoat, sacrificed by his own Army, a person who should have ignored what he perceived as orders to commit an illegal act. One can understand, one can sympathize, and one can't overlook that 347 people, most of them innocent, were slaughtered. The American military and the American people do not like to think of themselves that way, and it's true.