The lone highway that led to Woodstock was jammed with traffic, so the Who left the hotel early to play its Saturday night show. When the group arrived, word was out that bands weren’t getting paid; the promoters had decreed it a free show and stopped trying to collect tickets because so many people had turned up. The Who refused to go on until it received a cashier’s check, but all the banks were closed.

While promoters scrambled to find money and the wait stretched out, the band found trouble, as it often did. The drummer Keith Moon and the bassist John Entwistle dropped acid and partied in the back of a station wagon with a pair of young female fans. The guitarist and chief songwriter Pete Townshend drank a cup of coffee backstage, and realized it was spiked with acid. When the singer Roger Daltrey took a break from his bottle of Southern Comfort to drink some tea, he, too, began to hallucinate.

Finally, after a wait that totaled 14 hours , the Who went on early Sunday morning and played its new album, the epochal rock opera “Tommy.” Moments after the set finished, the activist-prankster Abbie Hoffman, also high on LSD, crashed the stage, and said, into Townshend’s microphone, that the focus shouldn’t be on music, but on the MC5 manager John Sinclair, who was in prison on a minor marijuana charge. Townshend, according to his memoir, “Who I Am,” “knocked Abbie aside” with his guitar. The crowd roared at Townshend’s act of non-nonviolence. After years of struggling commercially in the United States, the Who had found a way to establish who it was.

In a phone interview from his home in East Sussex, England, Daltrey reflected on what he’s called the band’s worst set and his suede “Tommy” suit. These are edited excerpts from the conversation.