December 6, 1969: The Rolling Stones Play Altamont
On this day The Rolling Stones played the Altamont Speedway Free Festival and essentially ended the Summer of Love in one vicious swoop.
Event staff had hired the Hell's Angels motorcycle gang to be security at the event, which attracted roughly 300,000 people. Unfortunately, the Angels spent most of their time taking drugs and getting drunk. By the time the Stones were playing the Angels were opening fighting with audience members and biker Alan Passaro stabbed 18-year-old Meredith Hunter to death when the later brandished a gun. Passaro was originally charged with murder until video footage surfaced showing Hunter waving a gun. Passaro was then acquitted as his actions were deemed self-defense.
Some of that video would make its way into the Stones tour documentary Gimme Shelter which would debut exactly a year later. The doc captures the disorganization around the event and its slow descent into chaos.