King Crimson's daring debut remains prog's standard bearer, the best example of a then-emerging movement that sought to combine European musical concepts with rock 'n' roll.

In the Court of the Crimson King, released on Oct. 10, 1969, was also a template for how King Crimson would operate, as their lineup almost immediately flew apart. The core pair of Robert Fripp and Greg Lake was all that remained by the time King Crimson set about recording a follow up. By then, In the Court of the Crimson King had already soared to No. 5 on the British charts, the Top 30 in the U.S. and into lore as a pioneering achievement in rock.

"At that time, nearly all the British bands were using the blues or soul music – American music – as their influence," Lake once told Gibson. "Since that well had been visited so many times, we decided we would try to use European music as our base influence, in order to be different. Robert and I – and [multi-instrumentalist] Ian McDonald, for that matter – had all been schooled in European music. We understood it. We played Django Reinhardt, and we did Paganini violin exercises and so forth. Even though I loved American music, and had played it throughout my youth, it was very easy for me to adapt to using European music as the basis for new creations."

Underneath, as on songs like "I Talk to the Wind," there remained a steady foundation of folk or rock. But King Crimson had added a conceptual expansiveness more associated with classical. "To me, progressive music, the reason that came about was introducing different influences into basic rock music – the rock format of guitar-bass-drums, bringing in different influences, which is what King Crimson was, really," McDonald later told Big Bang. "That's what's underneath, incorporated into what's basically a rock 'n' roll band."

Robert Fripp says this unique mixture came to him in pieces – he'd worked at a hotel, for instance, where the sounds of a dance orchestra echoed through the halls – and then, almost all at once, when, by chance, he heard the colossal ending the Beatles' "A Day in the Life" on Radio Luxembourg. "It was terrifying; I had no idea what it was," Fripp told Perfect Sound Forever. "Then it kept going. Then, there was this enormous whine note of strings. Then there was this colossal piano chord. I discovered later that I'd come in half-way through Sgt. Pepper ... My life was never the same again."

Listen to King Crimson Perform 'Epitaph'

Fripp started making connections between things like Jimi Hendrix and Bartok string quartets. "My experience was of the same musicians speaking to me in different dialects – one musician speaking in different voices."

And with drummer Michael Giles, McDonald, lyricist Peter Sinfield and – in particular, it seemed – Greg Lake, Fripp had found a group of collaborators who were hearing it, too. The result, Fripp said, was simply magical. "As I heard it expressed later and even now, it was as if the music took over and took the musicians into its confidence," Robert Fripp told Perfect Sound Forever. "That is by no means the last time I felt in that position somewhere between heaven and earth – but that was the first time."

Greg Lake and Robert Fripp had grown up together, and had even gone to the same guitar teacher. They spoke a common musical language, even if they were speaking in a way that the wider world hadn't yet come to understand. "By the time King Crimson was formed, we were like two peas in a pod – like mirrors," Lake told Gibson. "He knew exactly what I knew, and I knew exactly what he knew. That was one very strange component of King Crimson. The other was that Ian McDonald had never been in a rock band before. He came from the military, from a military brass band. That was a bit peculiar. King Crimson was not an everyday sort of band."

Some of what they created, like the crunchy, futuristic "21st Century Schizoid Man," sounds eerily prescient – as relevant today as it was strange and wondrous back then. That song, in fact, has been one of the few constants for an ever-changing group. "'Schizoid Man,' for me, was intelligent heavy metal," Fripp once told Reflex Magazine. "It was very very hard to play – in its time. Technical standards have come forward now, of course. It was so hard to play, and it was so terrifying."

The subsequent "Epitaph," meanwhile, has a similarly dystopian theme, but with its sweeping use of Ian McDonald's Mellotron, a completely different feel. That was, in fact, the hallmark of an album that worked with a endlessly fascinating musical palette – personified both in the otherworldly guitar of Robert Fripp (sometimes delicate, other times eruptive) and in McDonald's dizzying arsenal of sounds. "I'm always biased towards the first album, I unashamedly have to say," McDonald told the Artist Shop, "and I think the best song on that album is 'Epitaph.' It's my favorite track and, to me, it's Greg Lake's best vocal anywhere."

Listen to Giles, Giles and Fripp's 'One in a Million'

"Moonchild" shifted seamlessly from a bucolic tableau toward a striking moment of free-form improvisation – so free, in fact, that you can hear a reference to Rodgers and Hammerstein's "Surrey With the Fringe on Top" within Fripp's guitar excursion. Perhaps best known of all was the title track, one of just two U.S. charting singles for King Crimson – and a triumph of episodic conception.

Taken of a piece, In the Court of the Crimson King couldn't have been much different from the preceding Giles, Giles and Fripp, this quaint, often unfocused group that featured Fripp and Michael Giles, with McDonald as an occasional collaborator. Their lone release, 1968's The Cheerful Insanity of Giles, Giles and Fripp, finds three of King Crimson's future players unable to find a similar balance a heady blend of folk, classical, pop, psych-rock and comedy. "I think we were just coming out and being ourselves, instead of operating within boundaries that other people had created," Giles told Aymeric Leroy. "We decided to do away with those boundaries."

King Crimson stood just as separately from the surrounding scene, too. "We weren't involved in the hippie movement, or the flower power, or drugs, or 'Swinging London,' Giles added. "We were somehow outside that, just concentrating on the music. Of course, we played, and we had access to all sorts of situations that 'Swinging London' was doing – but we didn't come from this environment."

In time, King Crimson's outsider brand of rock, as thoughtful as it was unlike anything else at the time, began to grow in popularity. In the Court of the Crimson King remains the group's best-selling U.S. album and second-highest charting U.K. release. "There was a sort of underground cult following, which came from nowhere and grew and grew," Giles told Aymeric Leroy. "It was quite surprising to us all, because all of us had spent probably the previous five to 10 years without it. So, it was quite overwhelming – overwhelming and humbling."

Both Giles and McDonald left soon after, later releasing a co-led self-titled 1971 recording. Giles also appeared as a guest performer on King Crimson's 1970 follow-up album In the Wake of Poseidon, but by then Lake's membership was ending, too.

Listen to "In the Court of the Crimson King"

"We were only together, the original King Crimson, for one album and one tour," Lake told Rolling Stone. "The tour went around England and it also went to the United States. When we reached the end of the tour in the U.S.A., Mike Giles and Ian McDonald, they decided they didn't much enjoy life on the road. I think they particularly didn't like flying, and they just didn't like travel and the whole hectic life on the road."

Fame, it seemed, had come too fast – or, for Ian McDonald at least, too soon. "Crimson went from total obscurity, living off seed money from a relative to worldwide fame in six months time," he told Perfect Sound Forever. "I was young then, and it was too much for me. If I took some time to think about it and gather my thoughts, I would have done things differently."

The first of what would become a series of cataclysmic shifts for King Crimson was underway. McDonald would stop in to lend a hand on 1974's Red, even as a subsequent lineup dissolved. His initial departure, however, had hit Greg Lake hard.

"I just didn't feel good about it because Ian, particularly, wrote a lot of the material," Lake told Rolling Stone. "Also, Mike was a great drummer. They were so fundamental in the makeup and the chemistry of the band. I just didn't feel it was honest to get two new people in and pretend that nothing had happened. I said to Robert, 'If you want to form a new band, I'm happy to do that. But I just don't feel comfortable carrying on with the name King Crimson.' He said, 'Well, do you mind if I do that?' I said, 'No, not at all. If you want to do it, that's fine.' So, that's what Robert did."

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