There were many factors that led to The Beatles splitting up by the end of the 1960s, but one of the primary reasons was John Lennon‘s growing activism. By ‘69, he cut a very different figure from the one that had emerged onto the scene in ‘63. He was a far cry from the poster boy of pop-rock, with an innocently trimmed mop top and a smile custom fit to win over young fans and their conservative parents. Once he got a peek behind the curtain of …