Robert Montgomery
He had an outstanding war record commanding PT boats. He also was the navigator on a destroyer at D Day. This accounts for the great conviction he brings to the role. I had the pleasure of meeting him once.
Wayne, as we all know, did not serve in the war. Joel McCrea didn't either and would not play in war films. But that didn't stop Wayne.
After the war, every Memorial Day weekend Ford would give a patriotic party at a property he owned outside LA. Wayne was not invited to these parties.