One of the worst things he did was almost cost us the war in the Pacific because he refused to admit that our interest lay there and not in Europe. He sent most war materials to Europe in the early days of the war and left the guys in the Pacific hanging, Guadalcanal is a case in point.
He had his head shoved so far up Churchill's butt that he couldn't see daylight. The war in Europe would never have happened if England and France would have shown some guts in the beggining and stood up to Hitler.
Even so, the English would have won it without our help, because Russia would have beaten Germany eventually and the English would have been able to land in France after Germany was beaten down a little more by Russia. We could have stayed out of the European war altogether and ended the Pacific war sooner, but FDR did things his, illegal, way and screwed the US in the process and we are still paying for his blunders and stupid social programs.
This thread seems to bring out the paleo nutcases.
1. No America. No D-Day. Period. Only American money, numbers, and munitions made that possible. By itself, Britain could only manage a Dieppe, a Crete, or a Narvik.
2. No interest in Europe ? Had Hitler won the first flag on the moon would have had a swastika on it. Germany would have been a far more powerful geopolitical rival than the Soviet Union ever was.
3. Cost us the war in the Pacific ? More bilge. Japan simply did not have the resource or industrial base to stay abreast of American production. Or even close. America outproduced Japan navally by a factor of 16 to 1. Japan had noplace to go but down. Germany, on the other hand, had a very powerful industrial economy and a magnificent army that had to be collapsed from both sides to be beaten.