RBJ, Barker wasn't at the site of the massacre--was in a helo and then at the battalion ops center. Pretty clear that he either falsified or deliberately with-held info later that day, but again, that is different than ordering or participating or observing and failing to stop the crime.
Calley's platoon represented one of 10-15 combat platoons in Barker's battalion task-force, depending on how it was configured that day. It is no reflection on Barker that the incident occurred--very difficult for a battalin commander in combat conditions to know what is happening in every one of his platoons. Afterward, his conduct in regard to checking and investigating and reporting is pretty damning. As he was killed shortly thereafter we'll never get the whole story.
Kosta, apparently we're talking past each other--I agree that it wasn't just Calley doing the killing--I'm not excusing his soldiers--I'm saying that Calley as the officer directly in charge had a responsibility to enforce discipline and ensure orders were carried out. Instead he did the opposite. His offenses were the most egregious.