Yascha Mounk in Persuasion:
In January 1941, the world found itself in the darkest depths of World War II. Nazi Germany had conquered Poland and France. It remained allied with Japan and the Soviet Union, and now seemed on the verge of subduing the United Kingdom. The stakes were existential and the outlook increasingly bleak.
In the United States, Franklin D. Roosevelt was pushing for America to come to the rescue of civilization. Against strong domestic opposition he supported Britain with the Lend-Lease Act and was readying the American armed forces for a potential entry into the war.
It must at the time have been tempting to condemn all Germans for the actions of the Nazis, who had after all gained power in good part because of their strength at the ballot box. But rather than ascribing collective guilt to all Germans—as, shamefully, his administration was soon to do in the case of Japanese-Americans—F.D.R. recognized the distinction between Germans who supported and Germans who opposed the Nazis. He courted exiled dissidents and, at the beginning of that fateful year, went so far as to invite one of the most famous of them for an overnight stay at the White House.
More here.