Answer:
Jack Mandelbaum was 13 years old when the Nazis invaded his native Poland in 1939.
Step-by-step explanation:
In August 1939, as the Nazis were about to invade Poland, Mandelbaum was 13 and living in the Polish port city of Gdynia. Mandelbaum says his father worried that the port would be attacked, so he sent his wife and three children to stay with relatives in the countryside.