Feigele Peltel grew up in a working-class Jewish family in Warsaw. She joined the Jewish Labor Bund as a teenager. After the German occupation of Warsaw in 1939, the Peltels were subjected to persecution. In 1940 they had to move into the ghetto and suffered from hunger, cold, and terror. Her father died of pneumonia in 1941. In 1942 Peltel’s siblings Chaim and Henia and her mother Hanna were deported to Treblinka extermination camp.
In the Warsaw ghetto, Peltel joined the Jewish resistance. As a courier for the Jewish Combat Organization (Żydowska Organizacja Bojowa), she smuggled messages, weapons, and ammunition into various ghettos in Poland, under a false name. Peltel helped Jews to escape from the ghettos and arranged hiding places for them. She often had to bribe Polish informers so as not to be betrayed to the occupying Germans.
After the Warsaw Uprising in 1944, Feigele Peltel and her boyfriend Benjamin Międzyrzecki fled to the countryside. They survived there, posing as a Catholic couple. After their liberation in early 1945 they married, emigrating to the United States in 1946.