This was the infamous Altamont Festival in 1969 which was hijacked by Hells Angels resulting in a murder during the Rolling Stones set who were headlining the whole thing. The whole Summer of Love coming to an end was precipitated by this Festival. It took place after Woodstock but was a complete contrast.

I really liked Jefferson Airplane in those days. White Rabbit was a real anthem of 1960s counterculture and Bless its Pointed Little Head, for me, is one of the best live albums ever.