On Saturday morning, the rain stopped just as Quill, the opening act on a day that was to be devoted to rock ’n’ roll, plugged in. As the morning sun began to dry things out, the little-known Woodstock-area band (on the bill because they’d played some local shows for Lang to build awareness about the upcoming festival) played a 40-minute set that betrayed a distinct Zappa influence. They went over quite well, considering the soaked and mud-caked condition of the throng. It’s hard to say whether inclusion in the movie would have benefited them, as it did Melanie and others who made the cut.

Country Joe McDonald was prevailed upon to do a few songs by himself, because the next act wasn’t ready. He sounded surprisingly earnest on “Donovan’s Reef” before getting the crowd fired up with the salacious, “Gimme an ‘F,’” etc., “Fish Cheer” on the way into the antiwar screed, “Feel Like I’m Fixin’ to Die Rag.”

Then it was time for Santana’s big moment. The baby band’s debut album hadn’t yet been released, so few people outside the Bay Area had heard of them, but Bill Graham, a big supporter, had used his considerable clout to get them on the bill. After the band came in by chopper that morning, Carlos Santana ran into Jerry Garcia, who informed the bandleader that the Dead were slated to play right after Santana but wouldn’t be going on until 2 in the morning, meaning the Latin rockers had till midnight to chill out. So Santana took a hit of mescaline.

“I thought, ‘If I take it now, by the time I come to play I’ll be coming down, and life is beautiful,’ you know?” Carlos recalled. “Wrong! As soon as I took it, and I turned on, all I can remember is some face saying, ‘You gotta go on right now. If you don’t play right now, you're not gonna play at all, period.’ So I was really peaking, and all I can remember was praying, the same as I always do when I'm in trouble: ‘Lord, please help me stay in tune and in time!’”

Santana may have been baked, but the only evidence of his delicate condition is the freakish expression on his face in the film footage as he solos through “Soul Sacrifice.” The visceral rhythms pounded out by the percussionists and drummer Mike Shrieve got the throng moving, and Carlos seized the moment, shooting out arcs of passionate single-string riffage.

John Sebastian’s name hadn’t been on Lang and Kornfeld’s list, but he was hanging out backstage anyway, so co-emcee John Morris asked him if he was up for playing some tunes, and Sebastian was “too whacked to say no,” as he put it. So it was that the former leader of the Lovin’ Spoonful strolled (or floated) onstage in his tie-dyed duds and played a memorable solo set, punctuated with stoned-out shtick, some of which wound up in the film, providing one of its defining moments. As we can tell now, Sebastian was totally on it despite being on it, bringing palpable feeling to his Lovin’ Spoonful ballad “Darlin’ Be Home Soon.” He later urged the crowd to “Just love everybody around ya’ and clean up a little garbage on your way out.”

Offbeat British blues unit the Keef Hartley Band cranked up the volume in a typically meaty performance of the slow blues “Too Much Thinking” from the group’s then-new debut album, Halfbreed, heard for the first time. Formed by drummer Hartley, a graduate of John Mayall’s Bluesbreakers, the band was fronted by singer/guitarist Miller Anderson and featured a pair of jazz horn players.

Then, finally, the Incredible String Band played their makeup date. Beyond their decision to perform only material from their not-yet-released Changing Horses album, Robin Williamson and Mike Heron’s delicate acoustic music seemed overmatched considering the mere presence of this huge crowd and amid the surrounding rock bands. But we know now that the duo’s performance was charming, if not sufficiently powerful for that particular moment.

Canned Heat took the stage and launched into a downright sensational set—so strong, in fact, that it makes one wonder why the band isn’t more revered. What Canned Heat could do as well as any rock band was to get into a groove and work it, as they did so irresistibly on the nearly half-hour-long jam that would be dubbed “Woodstock Boogie.” From the perspective of 50 years later, their pleasingly monolithic and altogether mesmerizing performance of this song brings to mind an earthier and friendlier Velvet Underground working their way through “Sister Ray.” In typical hippie fashion, Canned Heat was all about just going with the flow, said Bob “Bear” Hite, the band’s co-frontman, along with guitarist/harmonica player Al Wilson: “We’ve always just fallen into something within a couple of days and then just gone out on the road and played. Sometimes it’s shown it, and sometimes it’s been incredible. [During] the Woodstock performance, although there were a couple of tunes which weren’t too good—‘Going Up the Country’ was one of them—there were some which were killers, stone killers.”

Janis Joplin was out on her own after breaking through in front of Big Brother & the Holding Company, and the bulk of her Woodstock set revealed a relative lack of connection with her newly formed backing group, the horn-augmented Kosmic Blues Band. But Janis exhibited the controlled abandon that made her such an enthralling performer with the culminating trio of showstoppers “Work Me Lord,” “Piece of My Heart” and “Ball and Chain.”

Mountain, whose debut album wouldn’t appear until 1970 (their relative obscurity at the time ruling out an appearance in the movie or on the first soundtrack album), played their fourth live performance ever and surprised the crowd with a torrid set of high-octane rock that picked up where Cream—whose producer, Felix Pappalardi, was the group’s founding member—had left off. As with Canned Heat, Mountain warrants a serious reassessment based on the utter authority of their performance. Considering other big acts were still holding out, it makes sense that they were the only new addition to Woodstock 2. This new collection adds the monumental “Theme From an Imaginary Western,” written by Cream’s Jack Bruce and sung by Pappalardi, to the previously released “Blood on the Sun” and the untitled piece that would later be named “For Yasgur’s Farm.”

Deadheads look back on The Grateful Dead circa 1969 with special fondness, and their much-booted Woodstock set was representative of this peak period, if not quite achieving godhead—but it didn’t start out that way, as equipment problems stopped them in their tracks whenever they tried to get something going. The stage setup hadn’t been properly grounded, and whenever Garcia and Bob Weir got near their mics, they were zapped by a jolt of electricity—not something you’d want to experience while tripping. “Jeez!” Garcia shouted at the road crew. “I’ve just been hit by lightning!”

Once the problems were solved, the Dead got in sync, as the second half of the set—including an a 19-minute “Dark Star”—was loaded with passages of tripped-out splendor. In retrospect, the experience took on a cosmic significance for Garcia. “The thing about Woodstock,” he blissfully reflected, “was that you could feel the presence of the invisible time travelers from the future who had come back to see it.”

Despite John Fogerty’s later assertions that Creedence Clearwater Revival was a somewhat limited band, the two-guitar quartet was tightly wound, totally rockin’ and all business—the intense Fogerty barely said a word to the crowd. In short, these guys delivered, even under these trying conditions, no doubt toughened by having played several outdoor, multiple-billed gatherings earlier in the summer. Creedence collected $10,000 for the appearance, but they refused to allow their performance to be incorporated into either the follow-up movie or its soundtrack album. Had they agreed, this blistering performance would have gone down as one of the weekend’s high points.

Sly & the Family Stone stole the show with their wildly inventive merger of soul, funk and flower power. Like their records, their galvanizing performances were dense with embedded hooks—the hot-potato trading off of lead vocals, the staccato horn riffs, the archetypal popping attack of Larry Graham’s bass lines, the celebratory lyrics, which espoused community and diversity, the acid-rock flourishes and the racing rhythms. From the stage, they looked out on hundreds of thousands of bodies writhing rhythmically to their phat grooves.

“Sly was playing his very happy and funky soul music, and everybody was on their feet,” wrote rock critic Mike Jahn, who was covering Woodstock for Time magazine. “Everybody [was] standing and dancing or just bouncing up and down. It was beautiful. He came onstage at exactly the right moment. Everybody was dancing together. A few people had lit sparklers and tossed them high into the air each time Sly yelled ‘higher!’ Curious people, these flower children and their drugs! But it was beautiful. People really felt together. They walked and stood and hugged together and it was good. I felt like crying. It was very beautiful, at that moment, very beautiful.”

Most of Jahn’s review “was about Sly’s coup of the night before, but some of it was given to a negative review of Janis Joplin's backup band.”

The Who arrived at midday but were told they wouldn’t be going on until the wee hours of Sunday morning. The bandmembers were given snacks and beverages; no one bothered to inform them that everything had been spiked with acid.

When they finally took the stage at around 4 a.m., Pete Townshend started things off by kicking a cameraman, who turned out to be Woodstock director Michael Wadleigh himself. By then the monitor system had crashed, so they couldn’t hear themselves, resulting in some tuning issues, but also so angering them that they played with even more aggression than usual. Then, in the middle of the 25-song set, as the band blasted through Tommy, leftie activist Abbie Hoffman suddenly appeared onstage just before “Pinball Wizard” to harangue the crowd about the plight of MC5 manager John Sinclair, who’d been imprisoned in Michigan for possessing a couple of joints. He seized the mic from Roger Daltrey and started a stoned rant. Thinking he was another whacked-out fan rushing the stage, Townshend aimed a kick at Hoffman’s butt, whacked him in the head with his Gibson SG and snarled, menacing snarl as Hoffman fled: “Fuck off my fucking stage!” Townshend later joked that it was “the most political thing I ever did.”

Townshend later summed things up in characteristically acerbic—and distinctly non-Aquarian—terms: “What they thought was an alternative society was basically a field full of six-foot-deep mud laced with LSD. If that was the world they wanted to live in, then fuck the lot of them.” Townshend claimed he wrote “Won’t Get Fooled Again” as a direct response to his Woodstock experience.

“Fuckin' awful,” was Townshend’s blunt assessment of the experience, while Daltrey called it “the worst performance we ever did.” It was also among the most significant performances of the band’s career.

Who roadie Bob Pridden was on the side of the stage as his employers stalked off. “Everyone was out of their brains,” he said of the Jefferson Airplane’s roadies as they set up the amps. “They were moving around like snails, totally out of it. They’d put up an amp, stand back and admire it. It was an extraordinary thing. Woodstock was a mess. Though it was a big break for the Who, I don’t think any of them enjoyed it.”

The Who were a tough act to follow, but the Airplane were up to the challenge. “Good morning,” said a remarkably sunny-sounding Grace Slick as the band started what turned out to be a scintillating set at around sunup on Sunday morning in front of 400,000 muddy, stoned, hungry and exhausted fans. Opening up with a hopped-up take on Fred Neil’s “The Other Side of This Life” that may be the strongest performance of the song ever captured on tape, the Airplane blazed through a set that included their hit “Somebody to Love” and the recently penned fist-waver “Volunteers.”

One other band, proto-metal outfit Iron Butterfly, had also been booked to play on Saturday. Production coordinator John Morris is said to have received a telegram from the band, stating, “You will send helicopter to LaGuardia. Pick us up, bring us back. We will go immediately onstage, in front of everybody else, and then we will be given a helicopter and flown back.” Morris’ reply was brief and emphatic: “Fuck Off.” So it was that the band missed its chance at grabbing a piece of history.