LOL-- WWII history is obviously not your forte. ANY President of any party in office in a war would have pulled the country out of the Depression. Do not delude yourself with that simplistic reason.
The Progressive isolationists kept us out of the war for far too long. It took a direct attack to get us in the war.
Britain still remembers us staying "neutral" when they were being blitzed.
Successful Trading is the art of minimizing long term risk and maximizing capital allocation.