It took the largest organized concert of all time to make a Led Zeppelin reunion happen.

Unfortunately, after the death of a key member and five years away, they didn't rise to the occasion on July 13, 1985 at Live Aid in Philadelphia.

Robert Plant, then in the midst of a tour behind his solo album Shaken ‘n’ Stirred, was the first to be approached. Organizer Bob Geldof originally asked him to consider performing a set with Honeydrippers. But when Plant phoned Jimmy Page, the Honeydrippers idea was abandoned pretty quickly. Instead, the two decided it might be fun to trot out some old Zeppelin material instead. Once bassist John Paul Jones caught wind of what was going on and asked to be included, the reunion that no one thought possible suddenly seemed imminent.

There were issues, however, before Led Zeppelin even hit the stage. “Robert announced that he didn’t want to do 'Stairway [to Heaven],'" Page’s assistant Phil Carlo said in Led Zeppelin: The Oral History of the World’s Greatest Rock Band. “Jimmy said to me, ‘I fucking knew this would happen. We’ve just got to play this game all fucking afternoon until we get up tomorrow morning, when he’ll announce that he’ll do it.’”

In the end, a festival-highlight performance by Queen changed Plant’s mind, and he decided to include the iconic song in the band’s set. But Led Zeppelin's problems were just beginning. Guest drummer Phil Collins only had a loose grasp of the late John Bonham's intricate and heavy parts. Worst still, Plant was hoarse, Page’s guitar was out of tune and the onstage monitors were busted.

“It was a disaster, really," Collins later admitted. “Robert wasn’t match-fit with his voice and Jimmy was out of it, dribbling. It wasn’t my fault it was crap. If I could have walked off, I would have. But then we’d all be talking about why Phil Collins walked off Live Aid — so I just stuck it out.”

Led Zeppelin, as with all of the acts that day, was slotted for a meager 20 minutes. That meant a three-song set that began with “Rock and Roll,” before continuing into “Black Dog” and culminating with “Stairway to Heaven.” They were met with rousing cheers, but Plant was miserable. “It was horrendous,” he told Rolling Stone. “Emotionally, I was eating every word that I had uttered.”

Time didn't heal this particular wound either. Nearly 20 years after Live Aid, Led Zeppelin declined to release footage of their performance for the official Live Aid DVD.

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