Although he isn't an American the name of Field Marshall Bernard Law Montgomery should be included as well.
It was Montgomery who planned D-Day and was in a large part responsible for it's success.
Last summer I finally got around to finishing reading Nigel Hamilton's three volume biography on Montgomery and I can tell you he cleared up many misconceptions in a number of areas but also showed what a complete professionial soldier Monty was. He was without a doubt, along with Field Marshall Alan Brook, the best the British had and without them D-Day may not have been the success it was.
Monty was an incredible military leader, his main problem in history though will always be the impression that he was a condescending pompous ass.