Photography helped the Civil Rights Movement progress in the early 1960s because it helped capture some of the chaos that was going on in the South at the time. The 1963 photos of Bull Connor's police dogs and firemen helped expose some of the more drastic reactions to the idea of desegregation. The widespread images of these events helped turn more Americans nationwide in favor of the Civil Rights Movement.
Vietnam was the first televised war, but the pictures of the early days of the conflict are what helped dramatize the war. I learned that the monk practicing self-immolation was the deal-breaker for JFK and Ngo Dien Deim. The Life Magazine special on the personal photographs of a week's dead during the Vietnam War was moving. The student movements of the 1960s and especially the 1970 Kent State Shooting helped capture and promote a youth culture of rebellion against the status quo.
The Space Race was entirely defined by photographs. The photographs of the dark side of the moon and of the Earth from space were globe changing. The world got to see the beauty of Earth from an outside view and it helped unite the Earth a little more by showcasing the nearness of each other as societies and nations.
The camera also helped reshape the legal system and its definition of evidence. The invention of crime scene photography helps to show the physical evidence in their places and the gore of a crime for jurors to use in their judgements. It also helps to show the sheer inhumanity of international war crimes such as the Holocaust, the Khmer Rouge's rampages, or the Rwandan Genocide.
Photographs shaped politics immeasurably because it showed the humanity of a politician and both the good and bad things they could do. The photo and television wars of JFK and Richard Nixon helped make the 1960 Presidential Election. Ronald Reagan's movie star personality and glamour helped sway the entire American public throughout the 1980s.