People tend to forget that Einstein wasn't just one of the smartest people of his day, but that he was also a very active supporter of the disenfranchised. Forty years after this letter, he volunteered as a character witness for W.E.B. DuBois (on a charge of "failing to register as a foreign agent"). The simple fact that he volunteered in this capacity led to the case being dropped. SOURCE. In the late 1930s, he also actively campaigned (successfully) for American and British universities to hire Jewish scientists who had lost their jobs under the Nazis. In short, the dude was way more awesome than his scientific accomplishments give him credit for.

EDIT: His lobbying not only kept some very intelligent people (and their families) from dying in concentration camps, but also very likely resulted in a large enough brain-drain that the Nazis were unable to complete their atomic bomb work before end of the war, even though they had a head start on the United States.