Discrediting the New Deal has always been a top priority for right wing ideologues because recognizing it's success threatens a number of their fundamental assumptions about economics and governance. Claiming that deficit spending did not end the Depression, but that deficit wartime spending did, only highlights the contradictions and inconsistencies that ideological correctness can provoke in the conservative mind. As you so correctly point out, war IS an orgy of deficit spending. It proves the point without question, at least for the short term.

At the time, the contemporary (and probably incorrect) assumption that "war is good for business" was not very widespread amongst conservatives. It was felt that it would lead to inflation, deficit spending, debt, higher taxes, and the production of materiel that, consumed in war, would not be purchased by consumers or used to generate additional wealth. These are not unreasonable assumptions by any means.

But it was also a consequence of a wartime economy that with millions of men under arms, wages would have to rise to handle the inevitable labor shortage. The idea of having to compete against each other to get and keep a diminished pool of skilled workers was anathema to the business community. This was "redistributing the wealth" with a vengeance! Until Pearl Harbor, the idea of a global crusade against fascism was not very popular with the business community either, especially since it meant helping out our major competitor in world trade, the British Empire, and saving our greatest ideological competitor, the Soviet Union.

The postwar experience that prosperity could follow the war, and that the great debt could be managed by sound policy and controlled inflation was a surprise to everyone. Most people feared a resumption of the Great Depression after the war ended, but sound management by both Republican and Democratic administrations (plus some very fortunate and unanticipated post-war conditions) gave us a long period of prosperity that lasted until the Reagan era, when debt in proportion to GDP began climbing again. As you also point out, conservatives had learned one thing during War, debt could managed, and it could be very profitable.

Thoughtful conservatives today can correctly point out that the Thirties were a different world, and so were the Fifties, and what worked then may not work today. Conditions are very different now. This is something modern liberals should certainly keep in mind rather than just blindly reprising their earlier successful strategies. But in todays's ideologically contentious environment, this sort of necessary dialogue is not likely to take place. And for THAT sad state of affairs, the conservatives must certainly accept full responsibility.