In September 1919, the year after the end of World War I, a German captain named Karl Mayr, who ran a propaganda unit in charge of educating demobilized soldiers in nationalism and scapegoating, received an inquiry from a soldier named Adolf Gemlich about the army’s position on “the Jewish question.” Mayr tasked a young subordinate named Adolf Hitler to answer. The resulting Gemlich letter, as it is known to historians, is believed to be the first record of Hitler’s anti-Semitic beliefs and has been an important document in Holocaust studies for decades.