Ben Zion Kalb grew up in a religious Jewish family in southern Poland. The German Wehrmacht occupied his home town of Nowy Targ in November 1939. Kalb was beaten by German soldiers, and fled to Slovakia. To earn a living, he smuggled money and goods across the Polish-Slovakian border. In the summer of 1942, Kalb’s parents and brother were shot dead during the evacuation of the Nowy Targ ghetto.
With the aid of border smugglers, Kalb then arranged his fiancée Clara Lieber’s escape from the Bochnia ghetto near Kraków to Slovakia. The couple married in Bratislava in 1943. For safety reasons, they went into hiding in separate places. Kalb continued his rescue activities, through which his network brought several hundred Polish Jews to Slovakia. The rabbi Michael Dov Weissmandel helped to find safe hiding places for the escapees. During one escape operation, Kalb was arrested by Slovakian police and held in Kežmarok prison for two weeks. After their liberation, Clara and Ben Zion Kalb emigrated to the USA.