On this day, Dec. 6, in 1969, a teenager was stabbed to death by the Hells Angels during a Rolling Stones concert at Altamont Speedway.

More than 300,000 people attended the free show near Oakland, Calif., hoping it would be a peaceful “Woodstock West.” But the scene was decidedly ugly. Mick Jagger was punched when he arrived by helicopter. Jefferson Airplane singer Marty Baline got knocked out. The Grateful Dead refused to play.

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