Seventy-five years ago, a legendary act of heroism unfolded across the Oresund, the narrow body of water separating Denmark and Sweden. Over a fortnight in October 1943, the Danes defied their Nazi occupiers and smuggled out to safety more than 7,200 of their Jewish neighbors, making trip after trip across the waterway.

Almost unknown, however, is the story of Georg Ferdinand Duckwitz, a German bureaucrat in Copenhagen who risked his life to warn the Danish Jews of the impending roundup and made crucial arrangements to ensure their escape. Were it not for Duckwitz, who would later become West Germany’s ambassador to Denmark, the miracle on the Oresund would not have been possible.