Something happened.
Were the stars aligned in a certain way?
Was it the looks?
Was it the attitude?
Was it the hair?
To a degree yes, the latter played a big part as a startling point of difference in the music business is as valuable as gold.
More than anything, though, two of the chaps had a very clear and present spark when it came to writing tunes.
With a canny manager steering their path, they morphed from slick-haired rock and rollers into a pleasant-looking, cleanly suited pop group who wrote happy little tunes about holding hands and loving me do and advising some chap that "she" loves you.
They struck a chord ... in fact several chords ... and music, of the variety embraced by young people would never be the same again.
And all of a sudden everyone wanted to be a pop star.
Everyone wanted to form a group.
In 1963 a very powerful member of the American television fraternity by the name of Ed Sullivan caught sight of this startling new group with the oddly spelled name The Beatles and determined that they would make the sort of ratings impact on his Sunday night variety show that Elvis had a few years earlier.
Although at the time he had to be coaxed into getting Elvis on board as he wasn't too comfortable with the way the boy from Tupelo in Mississippi sort of wiggled his hips and made the girls scream.
All the Beatles had to do was shake their mops of hair.
So he had a chat with their manager Brian Epstein and the result was a firm and memorable place in history.
The Beatles made their first appearance on The Ed Sullivan Show on February 9, 1964 - 50 years ago last Sunday.
And for the following two Sundays they also put in appearances and the young of America were in raptures.
Everything changed. Music changed.
That debut appearance was a milestone in the history of American music, because it signalled the beginning of what was latterly described as the British invasion.
Bands like the Rolling Stones and Herman's Hermits also appeared later on Ed's show, as did the fledgling American bands whipped up by The Beatles breakthrough.
How powerful was the British influence on music?
Well, Jimi Hendrix was the opening act for ... Herman's Hermits ... when they toured over there.
And so, the title of a musical tribute set to screen on TV1 this Saturday night is no exaggeration.
The Beatles: The Night That Changed America - A Grammy Salute, TV1 at 9.40pm Saturday: It was 50 years ago today ... Mr Epstein told the band to play. And play they did. There's only two of the lads left now of course and they were both on stage together for this commemoration of the night they stepped into the spotlights of the Ed Sullivan Show. As well as messrs McCartney and Starr musicians like Dave Grohl, Katy Perry, the Eurythmics and Alecia Keys were among the line-up to pay tribute.
