When the Beatles broke up in 1970, to many it was more than the death of a band—it also seemed like the end of a dream. While the Beatles sang "All You Need is Love" during the Summer of Love, on his first solo album, John Lennon sang "the dream is over." A movement based on the slogan, "Do your own thing," could not sustain itself over a long period of time.

The Woodstock Arts and Crafts Festival in upstate New York in August 1969 had shown that half a million people could assemble, take drugs, and peacefully listen to rock and roll for three days. But in December at the West Coast version of Woodstock in Altamont, California, acid-crazed bikers called Hell's Angels mercilessly beat hippies who were assembled to hear the Rolling Stones perform. A black man was stabbed...