Two primal forces of rock collided for the first and only time on Aug. 27, 1965, as the Beatles met Elvis Presley. They'd first tried for an introduction during a celebrated 1964 U.S. tour; the stars finally aligned during a West Coast leg on the Beatles' return trip to America.

Beatles manager Brian Epstein and his Presley counterpart in Col. Tom Parker arranged for the event to take place at Elvis' Bel Air mansion. The rules were strict: No photographs or recordings were allowed. The Beatles were accompanied by Epstein and Beatles' press officer Tony Barrow. The King was joined by then-girlfriend and later wife Priscilla Beaulieu along with Parker and several members of the so-called Memphis Mafia, friends who traveled everywhere with Presley.

"I was pretty excited about it all, and we were lucky because it was the four of us and we had each other to be with," Ringo Starr remembered as part of the Anthology project. "He had all his guys around him, and we said, 'Hi, Elvis.' He was pretty shy, and we were a little shy, but between the five of us, we kept it rolling. I felt I was more thrilled to meet him than he was to meet me."

Both Paul McCartney and John Lennon admitted to no small amount of nerves.

"He showed us in, and he was great," McCartney said, also in Anthology. "I mean, it was Elvis; he just looked like Elvis. We were all major fans, so it was hero worship of a high degree."

Lennon, in a 1975 interview, said the Beatles were simply "terrified. He is our idol. I just remember sitting there and him playing the bass. And me thinking 'It’s Elvis! It’s Elvis!' It’s actually Elvis. He looked great then, no weight on him. He looked good."

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In keeping, things got off to a slow start, Memphis Mafia member Jerry Schilling said. "Things were a little awkward at first as introductions were made, and there was a lull when everyone first sat down together," Schilling wrote in Me and a Guy Named Elvis: My Lifelong Friendship with Elvis Presley.

"But Elvis broke the ice by saying to the Beatles, 'If you’re just going to sit around and stare at me, I’m going to bed.' Elvis and the guys began to laugh, and once the Beatles realized they were dealing with someone who shared their skewed sense of humor, everybody got along great."

Presley eventually pulled out a Fender bass, and began playing along with some favorite songs – including Charlie Rich’s "Mohair Sam." McCartney was impressed.

"That was the great thing for me, that he was into the bass," said McCartney. "So there I was: 'Well, let me show you a thing or two, El ...' Suddenly, he was a mate. It was a great conversation piece for me. I could actually talk about the bass, and we sat around and just enjoyed ourselves. He was great — talkative and friendly and a little bit shy. But that was his image. We expected that; we hoped for that."

Soon, Tony Barrow told the BBC, Elvis was calling for guitars to be handed out to Lennon, McCartney and George Harrison. He recalled someone bringing in a piano, too. "I can't remember all the things that they played but I do remember one of the songs was 'I Feel Fine,'" Barrow said. "And I remember Ringo – who, of course, didn't have an instrument – tapping out the backbeat with his fingers on the nearest bits of wooden furniture."

That's how the legend goes. Lennon also said that the group played and sang with Elvis Presley, but the other Beatles maintain that this loose collaboration simply didn't occur. “I never jammed with Elvis at all,” Harrison once insisted.

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The Beatles were subsequently introduced to Presley's future wife, though their time together was cut short.

"We played a bit of pool with a few of his motorcycle mates, and at about 10:00, Priscilla was brought in," McCartney said. "To demonstrate the respect that country-and-western people have for their wives? Sometimes it's a bit on the surface — as maybe their situation was shown to be later. It was like, 'Here's Priscilla.'

"She came in, and I got this picture of her as a sort of a Barbie doll — with a purple gingham dress and a gingham bow in her very beehive hair, with lots of makeup. We all said 'hello,' and then it was, 'Right, lads, hands off — she's going,'" McCartney added. "She didn't stay long. I can't blame him, although I don't think any of us would have made a pass at her. That was definitely not on — Elvis's wife, you know! That was unthinkable. She didn't need to be put away quite so quickly, we thought."

Harrison, at this point, was elsewhere. "I don't remember even seeing Priscilla," he said. "I spent most of the party trying to suss out from the gang if anybody had any reefers. But they were 'uppers and whiskey' people. They weren't really into reefer smoking in the South."

Four hours after the Beatles arrived, Col. Parker signaled the end of the evening by presenting each guest with a collection of Elvis Presley’s hits.

"It was one of the great meetings of my life," McCartney said. "I think he liked us. I think at that time, he may have felt a little bit threatened, but he didn't say anything. We certainly didn't feel any antagonism. I only met him that once, and then I think the success of our career started to push him out a little, which we were very sad about, because we wanted to co-exist with him. He was our greatest idol, but the styles were changing in favor of us. These were great times. So, even if you didn't enjoy all of the events that much, you could still go home to Liverpool and say, 'Well, you know who I met?'"

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