Recently read a book about Bill Graham and the Fillmore East & West by John Glatt (good read btw) and I learned a lot about the San Francisco scene I didn't know. Main thing is how the Jefferson Airplane really were the big drivers of the scene at that time. Anyway, I then started reading a lot about the festivals, esp. Altamont. A lot of people blame the Dead for the violence, since they refused to play because of the way things were spiraling out of control. That left a two+ hour gap between bands since the Rolling Stones didn't want to go on until the sun set. During this time, people started getting increasingly violent due to the lack of activity and drugs/drinking. Just thought it was interesting that the Dead were the band that refused to play, considering they had a major hand in getting the festival going, and I believe they also were the ones to suggest using Hells Angels for security.