Before World War II, Kolbe was active in promoting the veneration of the Virgin Mary, founding and directing several organizations and publications. In 1939, the friary he supervised near Warsaw provided shelter to Polish refugees, including Jews. In May 1941, he was arrested and imprisoned in the Auschwitz I camp.
In July 1941, a man from Kolbe's bunker had vanished, prompting the Nazis to pick 10 men from the same bunker to be starved to death to deter further escape attempts. (The man was later found drowned in the camp latrine.) When one of the ten cried out, lamenting about his family, Kolbe asked to take his place, and the wish was granted. After two weeks of starvation, only four of the ten men were still alive, including Kolbe. The cells were needed, and Kolbe and the other three were executed with an injection of carbolic acid.
Kolbe was beatified in 1971 and canonized in 1982. His feast day is August 14.