A quote often attributed to General George S. Patton (with several variations) "No bastard ever won a war by dying for his country. He won it by making the other poor dumb bastard die for his country."

Was this an actual quote of something that they made up for the movie Patton. It certainly seems like something the General would have said but I find different sources that differ on the subject. I used the quote but want to find if it was real or made up for the movie.