It actually goes (and I'd go with this first attribution, because it has been used by a lot of people)...
History is written by the victor.
~ Latin Proverb
Various citings found on the Internet:
"History is written by the winners."
~ Alex Haley, according to at least two print sources, from an interview with David Frost on April 20, 1972.
http://www.creativequotations.com/one/1422a.htm
The so-called lessons of history are for the most part the rationalizations of the victors. History is written by the survivors.
~ Max Lerner
History is written by the victors.
~Winston Churchill
"History is written by the victors."
-Machiavelli
"History is written by the winners. The books say the Indians were bad guys and the whites just needed a little land. It's like, Excuse me, let me take your car. I'm discovering it. I'm putting my flag on your windshield."
-- Mario Van Peebles