Jacob was living in Essen, Germany, when he met and married Erna Schumer, who, like him, came from a religious Jewish background. The couple had two children, Max, born in 1923 and Dora, born in 1925. Jacob worked as a salesman, and in the evenings he tutored students in Hebrew.

1933-39: In 1933 when Hitler came to power, Jacob went to Amsterdam to explore the possibility of the family moving there. However, Erna did not want to leave her three sisters who were living in Essen, and she also believed that the family would be safe if they remained in Germany. After nationwide pogroms in November 1938, the Ungers finally fled to the Netherlands. There, as penniless refugees, the Unger family was split up: Max and Dora were placed in the care of Jewish organizations.