So why did they welcome it? It is simple. Socialism and nationalism have long been and long will be the two political ideas which have most emotional appeal to people. And Hitler offered both in one package. That package would be powerfully appealing to this day except for the way Hitler's follies discredited it.
Adolf Hitler and the National Socialist German Worker's Party are the crazy relatives that the present day Left goes to great effort to avoid talking about.
The pragmatic brand of socialist (as opposed to the doctrinaire Marxist) will strike the pose that will have the most appeal in the target audience's minds. Thus in Germany, where the army was traditionally held in the highest esteem, the NSDAP assumed in public the form of a substitute army (ersatzarmee) with a mass of clean-cut men in spiffy uniforms marching about in disciplined formations. In the United States, where the standing military was traditionally looked upon with suspicion if not ridicule, the Left rejected the militarist paradigm. Unfortunately (for them, not necessarily for us), they assumed the form of what decent people came to call dirty-stinking hippies, a mob of unwashed savages attired in cast-off or otherwise ridiculous clothing who moved about in a sloppy mass.
The American Left in its manifestation as the Anti-war Movement had in effect taken on the modern form of a barbarian horde. But given that Socialism is essentially barbarian brigandage in modernistic makeup, why should we be surprised?
What are your questions on this block of instruction?