A Polish Christian, Karolina Maciag worked as the nanny and wet nurse for Mordechaj Przeworski, the youngest son of a Jewish family in Krakow. But in 1940, the Nazis forced all of the city's Jews to move into the Krakow Ghetto, including the Przeworskis. Two years later, the Nazis murdered Mordechaj's father and brother. Then in 1943, the Nazis prepared to liquidate the rest of the Jews in the ghetto. Mrs. Przeworski decided to save her youngest boy, Mordechaj, who was then ony nine years old. Mordechaj's mother had him jump out a window and run to his nanny's house.
Karolina welcomed the boy with open arms, despite being quite poor. Karolina and her own son, Poldek, lived in a small room in the yard of an apartment building. She also had a second son who was being raised elsewhere in Poland. It was this boy's identity that Mordechaj would use.
Karolina introduced Mordechaj to Poldek as his actual brother, and the two boys were raised as siblings. Despite Karolina's poverty, she did her best to care for the boy, whose family had all been murdered.
After the war, no one claimed Mordechaj, as he had no family left. But after a few months a friend of the Przeworski family found Mordechaj and sent the boy to Israel.
As an adult, Mordechaj kept in touch with Karolina, the woman who had selflessly saved his life, until she passed away in 1979. In 2011, Yad Vashem recognized Karolina Maciag as Righteous Among the Nations.