It is alleged that the Army knew the true nature of the situation far earlier but a Major named Colin Powell managed to suppress that knowledge.
Everyone in the Army at that time found their reputation tarred with this brush. Some decided this sort of thing would never happen again.
There's a wealth of information on the net about this event. You should bother to read some of it.
One of my cousins was an Arty Btry commander, and he saw some of his own men attacked at a nearby village.
Perhaps Calley was guilty of "lining up women and children" as you mention in the FR mail; but how many US military were attacked as they offered food to women and children. Maybe Calley erred on the side of caution, but I'm not quite sure why you brought him into this debate.
Don't need to read too much, since I saw enough to last me a lifetime.