Relatively unknown folk rocker Richie Havens wasn’t supposed to be the first act to play Woodstock, but when four other groups became snarled in the festival’s legendary traffic, the festival promoters convinced Havens and his band to take the stage hours after the concert was scheduled to begin on Friday afternoon.

Havens ended up performing an extra long set, literally playing every song he knew while Woodstock staff finished building the stage around him. After multiple encores, a sweat-soaked Havens came out to play one more song without any idea what it was going to be.

“When you see me in [the Woodstock movie] tuning my guitar and strumming, I was actually trying to figure out what else I could possibly play!” wrote Havens in 2009. “I looked out at all of those faces in front of me and the word ‘freedom’ came to mind.”

The high-energy, fully improvised song known as “Freedom / Motherless Child” energized the antsy crowd and set the tone for the rest of the festival.

Guitar genius Carlos Santana and his band were another group of newcomers who had recently recorded their first album before taking the Woodstock stage on Saturday afternoon. Their electric, Latin-infused Woodstock performance, driven by 20-year-old drummer Michael Shrieve, put them on the rock n’ roll map.

“I don’t remember if I had heard of Santana before Woodstock, but I thought they were tremendous,” says Carl Porter, who attended Woodstock not far from his home in Sullivan County, New York. “They moved the crowd like nothing I’ve ever seen.”

Santana’s six-minute, pulsating version of “Soul Sacrifice” stands out as the best song of the set. Rumor has it that Carlos, thinking he had hours before their set, had taken a dose of mescaline, a highly hallucinogenic drug, right before stepping on stage.

Whether it was the brain-altering chemicals or the natural intoxication of playing live in front of hundreds of thousands of people, Santana showed off the guitar solo skills that would earn him a spot in the Rock and Roll Hall of Fame.

The Who, one of the biggest acts of the 1960s British Invasion, took the Woodstock stage at 5 a.m. early Sunday morning after a funk-rock set by Sly and the Family Stone. Just a month earlier, The Who released Tommy, an ambitious, double album-length rock opera.

“I heard this thing and my mind was completely blown,” says Nancy Eisenstein, who attended Woodstock in part to see The Who play live. “They performed the whole Tommy album at Woodstock. The stage was dark, then we heard ‘See me. Feel me. Touch me. Heal me.’ And a blue spotlight shone down on Roger Daltrey in a white buckskin outfit. It’s a snapshot I’ll never forget.”

For folks who hadn’t heard Tommy yet, the musical highlight probably came during The Who’s encore set.

“This is kind of our hymn,” said a young Pete Townshend, as the band prepared for its final number. “It’s a song about you and me. We’re getting a bit old now… It’s a song called ‘My Generation.’”

After running through a rousing rendition of their best-known hit, the band transitioned into an extended improvisation called “Naked Eye,” featuring long guitar solos from Townshend backed by Keith Moon’s frenetic drumming. Townshend capped off the performance by bashing his guitar on the stage and then tossing it into the crowd.

Jefferson Airplane, a popular San Francisco act fronted by the inimitable Grace Slick, was next to take the stage around 8 a.m. on Sunday.

“I was a longtime time fan of Jefferson Airplane,” says Porter. “What a great way to wake up, to Grace Slick saying ‘Good morning, Woodstock!’”

Slick led the band through a raw and rocking 100-minute set that included their hits “Somebody to Love” and the Alice in Wonderland-inspired ode to experimentation, “White Rabbit.” Unlike other bands who got sloppy when playing live, Jefferson Airplane’s live rendition of “White Rabbit” was taut and terrific.

The soulful British rocker Joe Cocker released his debut album, named for his cover of the famous Beatles song, just four months before Woodstock. Paul McCartney remembers hearing it for the first time at a Saville Row studio in London.

“It was just mind-blowing,” said McCartney. “Joe totally turned the song into a soul anthem, and I was forever grateful to him for doing that.”

The seven-minute version of “With a Little Help From My Friends” that Cocker and his band sang to close his set at Woodstock is one of the most iconic live performances of all time. Cocker physically embodied the music, scream-singing in his guttural bluesy voice while completely reinventing the Beatles song as a gospel refrain.

It’s fitting that after Cocker finished his set, the skies over Bethel, New York erupted in an apocalyptic summer thunderstorm that drenched the crowd and delayed the music for nearly an hour.

The rabble-rousing Berkeley musician Country Joe McDonald brought the crowd back to life after the soaking with a rousing cheer known as the “Fish” cheer, but featuring another four-letter word. He then kicked into his anti-war folk anthem with its famous chorus:

“And it's one, two, three, what are we fighting for?

Don't ask me I don't give a damn. Next stop is Viet Nam.

And it's five, six, seven, open up the pearly gates.

Ain't no time to wonder why, whoopee we're all gonna die!”

Porter, who was about to ship out to the front lines, didn’t appreciate the sentiment, but McDonald goaded the crowd to sing along and ended up with hundreds of thousands on their feet and clapping along by the end.

Not everybody at Woodstock came for the music. Toronto native Linda Goldman was there to experience the scene—camping with hippie families from the Hog Farm, swimming in the pond—and to catch the occasional performance. A group she really didn’t want to miss, though, was The Band, which had started out as a rockabilly group in Canada.

“I remember sitting on a hill and listening to The Band,” says Goldman. “One of my all-time favorite songs is ‘The Weight.’ When I heard them do that, I was on cloud nine.”

Arguably the most iconic moment of the entire Woodstock festival was when psychedelic guitar rocker Jimi Hendrix’s played his legendary rendition of the United States National Anthem. Hendrix's performance was one of the last songs on stage at Woodstock. The exhausted Monday-morning crowd had dwindled to 30,000 when Hendrix and his backing band took the stage to play through hits like “Foxy Lady” and “Purple Haze.”

But for anyone who witnessed it—or has even watched the clip on YouTube—there’s no forgetting Hendrix’s haunting interpretation of “The Star-Spangled Banner.” Its melody is drenched in feedback and bombarded by whammy-bar sirens, wails, machine gun fire and auditory “bombs bursting in air.”

To drive the anti-war message home, Hendrix even inserted a bar from “Taps,” the military funeral hymn. Porter was standing just 30 feet from the stage when Hendrix made his musical statement fueled by American pride and protest.

Days before he was to head overseas into “a very uncertain future,” Porter believed Hendrix was playing the National Anthem just for him.