"Pepper was probably the one Beatle album I can say was my idea," McCartney told an interviewer. "It was my idea to say to the guys, 'Hey, how about disguising ourselves and getting an alter ego, because we're the Beatles and we're fed up. Every time you approach a song, John, you gotta sing it like John would. Every time I approach a ballad, it's gotta be like Paul would. Why don't we just make up some incredible alter egos and think, 'Now how would he sing it? How would he approach this track?' And it freed us. It was a very liberating thing to do."
However, aside from the quasi-military/band uniforms, the opening theme song and its reprise near the end, and Ringo's take as "the one and only Billy Shears" in With a Little Help from My Friends, these alter egos really didn't mean a whole lot to the overall effort. On the other hand, just looking at the cover gave you a very good view of how the group had grown from what they were.
So much happened in 1967, but this was one of the big things. It was truly a visionary breakthrough in pop music. And, by God, we expected no less. Rubber Soul had been great, but we were looking for revolution. And this album revolutionized music in a way that none other ever did. As most modern novels come from Ulysses, most modern pop music comes from the Sgt.