Do you really know anything about FDR
No I never heard of him.

Born in 1882, his only shot at war would have been the 1898 Spanish American War...and that would have made him too young. (Don't know if he personally supported that or not.) By WWI he was acting as the administrative head of the Navy and had been instrumental in setting up the Naval Reserve and preparing the Navy for war.
So he was young enough to quit and go join the army during WW1 then. Hes a chicken hawk. He was instrumental in getting the US involved in two world wars.