To control the Jewish population of towns they invaded, the Nazis established ghettos, walled sections of cities where they forced Jews to live in crowded, unsanitary conditions. By the end of 1941 most of the Jews of occupied Eastern Europe were imprisoned in ghettos.
The Nazis forced the Jews to pay for and build a wall around the Warsaw Ghetto in 1940.
Source: U.S. Holocaust Memorial Museum
A family portrait of the Balters in Ostrowiec Ghetto, c.1941. One son fled from Poland to Japan and enquired about his family through the Red Cross, prompting the Gestapo to order the family to be photographed. The picture was sent to Japan to demonstrate that they were fine. Herszel (3rd from left) survived the war but his father and two older sisters did not.
Source: JHC, courtesy of Herszel Balter