One wonders how different the course of the twentieth century would have been had the warnings about the Nazi government been received and acted upon in time. In the Garden of Beasts is, in part, the story of one such Cassandra — William Dodd, American Ambassador to Germany during the first few years of FDR's tenure, and of Hitler's rise to power.
He was disliked by the State Department because he disdained the good-old-boys club that ran it and their excesses. Their main concern was that he keep the Germans from defaulting on their debt to American creditors; his was doing what he could to moderate the German government and to encourage the liberal elements of German society that remained.
It's a sobering reflection on what results if we are willing to gloss over the warning signs of fascism, because we are either uninterested in its targets (the entire State Department, the ambassador and his family included, harbored some level of anti-Semitism) or because we are hopeful, assuring ourselves that the evil and corruption cannot sustain itself and will eventually collapse.