In “Sir! No Sir!” David Zeiger’s 2006 documentary about G.I. resistance to the war in Vietnam, Bill Short tells how revolted he was by having to count the bodies of enemy dead for his unit. When he refused to do it any longer, he was sent for psychological counseling. At the moment he thought he was about to be remanded for psychiatric confinement, the shrink, as Short refers to him, pulled a copy of the Nov. 9, 1969, New York Times from his desk and pointed to a full-page advertisement against the war signed by 1,365 active-duty GIs. Bill didn’t need a diagnosis, he needed a social movement — and there it was.