David Crosby reflects on the real meaning of the cultural milestone in the gripping new documentary, Remember My Name
Photo of Crosby, Stills & Nash
Credit: Tom Copi/Michael Ochs Archives/Getty Images

Most bands play their early gigs to a handful of bored patrons in an otherwise empty dive bar, but not Crosby, Stills, Nash & Young. They performed their second-ever concert on Aug. 18, 1969 to a wall of humanity at the iconic Woodstock festival. “This is the second time we’ve ever played in front of people, man,” Stephen Stills memorably told the crowd. “We’re scared s—less!”

It makes sense that they’d start at the very top. Each bandmate was famous long before they’d ever played together. Crosby had been a member of folk-rock pioneers the Byrds, topping the charts with “Mr. Tambourine Man” and “Turn! Turn! Turn!” before parting ways in the fall of 1967. Nash had scored several hits with the Hollies, one of the many so-called “British Invasion” groups who flooded American airwaves in the wake of the Beatles. Stills had been in the hugely influential L.A. group Buffalo Springfield, where he’d penned the protest anthem “For What It’s Worth (Stop, Hey What’s That Sound).”

When Crosby, Stills & Nash first joined voices during an informal hang at fellow singer-songwriter Joni Mitchell’s Laurel Canyon cottage in July 1968, it was love at first listen. While the last notes hung in the air, the first American super-group was born.

Photo of Crosby Stills & Nash
Crosby, Stills & Nash
| Credit: Michael Ochs Archives/Getty

The trio recorded their first album, which shot into the Top 10 in the summer of ’69 — but they were faced with a problem: touring was a necessity, and the songs were incredibly difficult for the trio to perform live. The elaborate harmonies were layered with multi-tracking, and Stills (dubbed “Captain Many Hands”) overdubbed a number of the instruments himself.

They would need to augment the band in order to perform concerts. Drummer Dallas Taylor and bassist Greg Reeves were brought on board, and Stills tapped his former Buffalo Springfield bandmate Neil Young, who was already emerging as a major solo force, to join the fold. CSN added a “Y” and they booked their first tour.

The 39-date trek began on Aug. 16, at the Auditorium Theatre in Chicago, with Mitchell as their opening act. Then they were off to the “Aquarian Exposition” that had kicked off the day before in upstate New York. Individually, they’d played festivals before (notably the Monterey Pop fest two years earlier) but as they helicoptered to the concert site in Bethel, New York, and gazed down at the sea of people below, they realized this would be different.

The playful disorder that reigned over the proceedings meant that the group didn’t hit the stage until just after 3 a.m., long after the festival had technically ended, and a healthy percentage of the original crowd had departed. But as Stills colorfully announced, they were indeed nervous — though not because of the multitudes stretched out in front of them.

Instead, they were more concerned with the small group that had gathered behind them. A circle of highly respected musical peers like Jimi Hendrix, Janis Joplin, Grace Slick, Robbie Robertson and Sly Stone gathered in the wings to see if this new band could bring the goods. As they launched into the sprawling “Suite: Judy Blue Eyes,” it was clear that they could. And they did.

At first it was just Crosby, Stills and Nash blending their voices with only two acoustic guitars for accompaniment. A cover of the Beatles’ “Blackbird” was followed by a trilogy from their debut — Stills’ “Helplessly Hoping,” Crosby’s “Guinnevere” and Nash’s “Marrakesh Express.”

They capped off the acoustic portion of their set with a new song, “4+20,” which would surface the following year on CSNY’s Déjà Vu. Neil Young, who felt that documentarian Michael Wadleigh’s cameras were a distraction and refused to be filmed, joined Stills for a brief Buffalo Springfield mini-reunion as the duo performed “Mr. Soul,” “I’m Wonderin’,” and “You Don’t Have to Cry.”

Then the full band returned for the rocked-up five-song finale (“Pre-Road Downs,” “Long Time Gone,” “Bluebird Revisited,” “Sea of Madness” and “Wooden Ships”) before sending the audience off for a few hours of sleep with a pair of acoustic numbers: “Find the Cost of Freedom” and “49 Bye-Byes.”

Their performance was a highlight of that legendary weekend, but Crosby cherishes a different memory. While speaking to PEOPLE about David Crosby: Remember My Name, a new documentary about his tumultuous life and unparalleled musical legacy, he opened up about the cultural milestone.

He recounts a memory that crystalized the experience, speaking in rapid-fire present tense as if the long-ago moment is unfolding in real time.

For more on Crosby’s incredible life and music, pick up the latest issue of PEOPLE, on stands Friday.