There are few historic events whose legends are more grossly different from the reality than the New Deal administration of Franklin D. Roosevelt. And there are few men whose image has been more radically different from the man himself.
Some of the most devastating things that were said about FDR were not said by his political enemies but by people who worked closely with him for years-- Secretary of the Treasury Henry Morgenthau being just one. Morgenthau saw not only the utter failure of Roosevelt's policies, but also the failure of Roosevelt himself, who didn't even know enough economics to realize how little he knew.
Far from pulling the country out of the Great Depression by following Keynesian policies, FDR created policies that prolonged the depression until it was more than twice as long as any other depression in American history. Moreover, Roosevelt's ad hoc improvisations followed nothing as coherent as Keynesian economics. To the extent that FDR followed the ideas of any economist, it was an obscure economist at the University of Wisconsin, who was disdained by other economists and who was regarded with contempt by John Maynard Keynes.
President Roosevelt's strong suit was politics, not economics. He played the political game both cleverly and ruthlessly, including using both the FBI and the Internal Revenue Service to harass and intimidate his critics and opponents.
It is not a pretty story. But we need to understand it if we want to avoid the ugly consequences of very similar policies today.