A Turning Point
The Tet Offensive was a turning point because it turned the American media and public against the war and made the military and Johnson seem like a liars after telling everyone we were winning, and the NVA and VC were unable to perform a major assault. Other than that it was a horrible loss for North Vietnam because they lost some of their best troops and they weren't capable of launching a significant attack after that.
The Democratic Convention
Assassination of Robert Kennedy
Assassination of Martin Luther King Jr.
This event was a turning point because the African Americans started to riot out for what happened to their leader. And they started being seen differently.
Election of 1968
This event was a turning point because Kennedy quickly gained ground in the race by winning primaries in Indiana and Nebraska. In June he won the crucial California primary.