Mordor inspired by Nazi Germany?

[Inziladun]

Rohan can be a more American role. They were fully roused to action after a grievous attack on their native soil (Helm's Deep as a sort of Pearl Harbor attack

Helm's Deep was not exactly a 'sneak attack'. The Rohirrim had already fought Saruman's forces at the Fords of Isen, which was where Théoden's son Théodred met his end. It must also be remembered that if not for Gandalf the victory at Helm's Deep would very likely not have occurred, and the King would have been captured or killed at Edoras. That said, I don't think Éomer can be compared to FDR. He was a military leader, perhaps more of a Patton, and had little influence on 'policy' decisions for the Rohirrim until very late in the War..