If this has been disussed at length before, I apologize.  It is something that has recently occurred to me.

The decline of the Elves in Middle Earth (or maybe it would be more accurate to say their departure from it) always fascinated me and puzzled me a litte. 

I could not think of a parallel from history or literature where one of the sides which were victorious in a war subsequently picked up and left. 

Then I thought of the British Empire.  It played a major part in winning World War II.  Then it pretty much  voluntarily shrunk as more and more nations got their independence.

I could be on the totally wrong trail here but I thought that since the British Empire was shrinking at pretty much the same time as Tolkien was writing LOTR, maybe it subconciously influenced the way he wrote the elves' tale.

I'd appreciate any thoughts on the matter.