The war did not pull us out of anything. The war destroyed the rest of the world, thereby making our undamaged capital more worthwhile . . . a result that the Nazi Germany attempted to achieve but the US actually achieved. Wartime GDP inrease was a statistic quirk: all the battleships, aeroplanes, bombs, and men hired to kill each other were imputed to have very high value in GDP count. The real living standards on the other hand declined, even among Americans: gasoline was rationed, new cars were not available for purchase, and moms had to work outside the house because the dads and sons were drafted into slavery to die half a world away.
Prosperity in the US only came after the end of WWII, and that's because the relatively undamaged capital goods in the US gave Americans a competitive advantage in claims on raw material compared to a devastated rest of the world. Even then, American prosperity in the 50's was only in comparison to the rest of the world's poverty, not in comparison to what Americans enjoyed during the earlier golden age of international free trade.
FDR did not save capitalism. Most if not all the economic woes that we face today can be traced back to FDR's policies: from the peace-time massive funding of the military-industrial complex, to the chronic budget deficit, to the mandatory Ponzi Scheme that destroys people's retirement savings through inflaiton while pretending to give them retirement, to the government manipulation in the housing sector, etc., etc., all of them trace back to the FDR administration and his boy-wonder social engineers. What they did was socio-fascist central planning, just like Stalin and Hitler did in their respective countries, far removed from free market capitalism.
