I've read on numerous writer blogs and sites that it's not the best idea. You see, people do judge books by their cover. And beside the book cover, the most important thing is the first reading session a reader has, which is within the bookstore, and which is usually the first few pages.

For your writing to be clear, and for the plot to be set up the right way it might seem useful to have a prologue. But as always, the readers come into the picture. We usually put down a book when the first chapter is all about history and ancient battles. Or even if the conflict isn't clear at the end of the first chapter.

Same goes for movies. Nobody likes one where there isn't any action at the start. You get bored easily if Indy doesn't wave his whip around five minutes into the movie, or if Captain America doesn't beat some bad guys after the logos.

It's your decision though. Books with prologues are better constructed (because the important part of the history is clear, and the reader can simply go back to the prologue to read it over again instead of going through all the chapters once again for the little hints), but do bore readers (I usually skip through them at the library) and scare away agents (as some of them say).