What the album actually represented was the band's arrival at the height of their compositional powers and the apex of their ability to distill their primary influences (folk, rock and blues) into something grander that faithfully encompassed elements of all three genres. And to do that, they had to go "country" � or at least into the countryside.

Until mid-1970 the group hardly had time to plan its moves. Less than two years in existence, Led Zeppelin had already made two albums and toured the U.S. � where Page acquired his storied "Number One" Gibson Les Paul Standard from Joe Walsh � five times, rising from clubs to arenas as their guarantees swelled from $1,500 to $100,000 a show. The modus operandi had been to grab their blues roots hard and hit the ground running, and it was only when they stopped in July for a five-week break in the action that Led Zeppelin III crystallized as something more.

Before that the group had tried to record "Since I'd Been Loving You," which appears in a pre-Led Zeppelin III live version on the Royal Albert Hall concert DVD, but couldn't nail its radical shifts in dynamics and intensity in the studio.

The acoustic "Friends," inspired by Page's tinkering with open C tuning, and "Immigrant Song" were also written, or at least ready to get crunched out in jams and on tape.

But sometimes the vibe just isn't right. Maybe, for Led Zeppelin in 1970, it was a matter of finding the right headspace. The group's most recent tour of the States had been a challenge. On the plus side, they set attendance records wherever they traveled and grossed well over a million dollars at a time when concert tickets were about the same price as a fast-food meal today. But the minuses included conflicts between the police and Led Zeppelin's counter-culture audiences in Baltimore, Vancouver, Pittsburgh and other cities. In Georgia and Texas, Plant and Page were taunted by rednecks when their bus stopped, and in Texas they were refused service at a restaurant because of their long hair and had a pistol pulled on them. Worse, in Canada, Page's beloved three-pick-up 1960 Gibson Les Paul Custom Black Beauty was nicked at an airport and still has never been recovered. He'd played the instrument since his years in the Yardbirds.

So when Plant suggested a July retreat to the ancient Welsh cottage Bron-Yr-Aur that he'd visited as a lad, he and Page packed up their families and headed to the country to find some peace.

After 18 months on the road playing at teeth-rattling volumes, the tranquility of the unelectrified cottage was welcome. It also seemed to be a perfect segue for the music they'd been listening to, which included a big helping of acoustic open-tuning wizards John Fahey, Burt Jansch and Davy Graham.

"That's the Way" ended up becoming a turning point in the upcoming album's direction. After Page and Plant mapped the song out at Bron-Yr-Aur it became a touchstone, dictating further acoustic explorations for Led Zeppelin III. Page developed the song in open G tuning, inspired by Muddy Waters and Robert Johnson, and that, in turn, fueled a search for new textures when they returned to the studio. When the song was recorded John Paul Jones shifted from bass to mandolin, and Page took turns at pedal steel and dulcimer.