Born on 15 February 1910 in Warsaw, Poland, Irena Stanisława Sendler initially grew up in Otwock, a town about 24 km southeast of Warsaw, where there was a Jewish community and being a kind hearted physician, his father used to treat the poor ailing Jews of the locality free of charge. After studying law for two years, she studied Polish literature at the University of Warsaw, but repeatedly refused employment in the Warsaw school system because of her radically leftist views and became associated with social and educational units of the Free Polish University, where she was influenced by activists from the illegal Communist Party of Poland. She took a job in a legal counseling and social help clinic and worked mostly in the field for helpless, socially disadvantaged women. However, the section was abolished by the government in 1935 and most of its employees, including Sendler, were absorbed into the Department of Social Welfare and Public Health.

Soon after the outbreak of WW II on 1 September 1939, the German authorities ordered the removal of Jews from the staff of the Social Welfare Department and also barred the department from providing any assistance to the Jewish citizens of the city.

Since then, Sendler and her activist colleagues became involved in helping the wounded and sick Polish soldiers and on her initiative the cell began generating false medical documents to help the ailing soldiers and poor families. In addition to that, to help Jewish families and children, who were excluded from their department's social welfare protection, she also created other false references and pursued schemes. However, the trick became practically impossible, when the Nazis drove around four hundred thousand Jews into a small area of the city designated as the Warsaw Ghetto and sealed the area in November 1940. As a result, the situation in the overcrowded ghetto started to deteriorate increasingly and the poor hygienic conditions, added to the shortage of food and medical supplies, resulted in epidemics and high death rates.

However, despite great personal danger, Irena devised means to get into the ghetto and help the dying Jews. As employees of the Social Welfare Department, she and her activist friend Schultz managed to obtain permits to enter the ghetto to inspect the sanitary conditions, especially to check for any sign of typhus, a disease the Germans scarred might spread beyond the ghetto and attack them.

They took advantage of the situation and under the pretext of conducting sanitary inspections, they started to bring medications and cleanliness items, even sneaked clothing, food and other necessities into the ghetto. Once inside the ghetto, she also established contact with activists of the Jewish welfare organization, who ended up on the Jewish side of the wall, and began to help them smuggle Jews out of the ghetto and helped set up safe and suitable hiding places for them.

As head of the children’s section of the Polish underground Council for Aid to Jews (Żegota), Irena and her network of 10 compatriots knocked on each door in the ghetto, requesting parents to give up their children for smuggling them out of the ghetto for their safety. Each child was given a forged Polish name and identity papers and was placed by Irena’s network with Polish families, in Rodzina Marii Orphanage in Warsaw and Roman Catholic convents in nearby Chotomów and Turkowice, after carefully recording in code their original names and placements for their identification after the end of the war.

For further safety, the children were often given Christian names and taught Christian prayers in case of verification by the Nazis. Lastly, Irena also took care to hide the secret list, containing the details of the smuggled children in empty milk jars, which were buried in the backyard of one of her co-conspirators.

Irena Sendler was arrested and brutally tortured by the Gestapo, the German secret state police, on 18 October1943, but despite everything, she refused to betray any of her comrades or the children they rescued. She was sent to the infamous Pawiak prison for further interrogation and beating and was shifted to another location for execution by firing squad. However, her life was saved by the efforts of her comrades, who bribed the German guards escorting her and she was released on the way to the execution. After her release in February 1944, she assumed a new identity and remained in hiding as a nurse Klara Dąbrowska, until the Germans left Warsaw, while continuing her work for Żegota. After the end of the war, she was awarded at least six decorations, which included the Gold Cross of Merit for the wartime saving of Jews in 1946 and the Order of the White Eagle, Poland's highest honour. But she became a public figure at the age of ninety, when she was rediscovered by a group from an American High School in 2000. Irena Sendler lived in Warsaw till her death on 12 May 2008.