In the days after the German army invaded on Sept. 1, 1939, his parents faced difficult choices: when to leave, by what mode of travel, and in which direction. Only later would his family learn that by driving south toward Romania, rather than heading east, they probably avoided being captured by the Soviet army and deported to Siberia. College-aged fascists engaged in “unprovoked random assaults on Jewish street vendors and passersby,” Dr. Bussgang wrote in a memoir. Gangs “attacked Jewish students with canes fitted out with razor blades. Some of these senseless beatings were fatal. I became afraid to walk...