Frankfurt was the first university the Nazis tackled, precisely because it was the most self-confidently liberal of major German universities, with a faculty that prided itself on its allegiance to scholarship, freedom of conscience, and democracy. The Nazis knew that control of Frankfurt University would mean control of German academia. And so did everyone at the university.
Above all, Frankfurt had a science faculty distinguished both by its scholarship and by its liberal convictions; and outstanding among the Frankfurt scientists was a biochemist-physiologist of Nobel-Prize caliber and impeccable liberal credentials. When the appointment of a Nazi commissar was announced . . . and every teacher and graduate assistant at the university was summoned to a faculty meeting to hear this new master, everybody knew that a trial of strength was at hand. I had never before attended a faculty meeting, but I did attend this one.
The new Nazi commissar wasted no time on the amenities. He immediately announced that Jews would be forbidden to enter university premises and would be dismissed without salary on March 15; this was something that no one had thought possible despite the Nazis loud antisemitism. Then he launched into a tirade of abuse, filth, and four-letter words such as had been heard rarely even in the barracks and never before in academia. . . . [He] pointed his finger at one department chairman after another and said, You either do what I tell you or well put you into a concentration camp.
https://www.facinghistory.org/resource-library/controlling-universities