By Adam Easton
BBC correspondent in Warsaw
Irena Sendlerowa recently celebrated her 95th birthday in her small room in a Warsaw nursing home.
Irena Sendlerowa is modest about her selfless actions
Among the flower-bearing well-wishers were a number of people who owe their lives to this tiny courageous woman.
They were among the estimated 2,500 Jewish children Mrs Sendlerowa and a small group of social workers rescued from the Warsaw ghetto during World War II.
She is a Polish Catholic who risked her life to save Jews during the Holocaust.
For doing so, she was awarded the title of Righteous Among the Nations by Yad Vashem, Israel's Holocaust remembrance authority.
Unlike her fellow Righteous, German industrialist Oskar Schindler, who was immortalised in Steven Spielberg's film Schindler's List, few people have heard of Irena Sendlerowa.
When the war broke out Warsaw was home to 1.3 million people, of whom 380,000 were Jews, making it
the largest Jewish community in the world outside New York. The Nazis moved quickly to identify and isolate the city's Jewish population.
Jewish-owned businesses had to be clearly marked and Jews had to wear armbands with the Star of David. Then, on 15 November 1940, Warsaw's German Governor Ludwig Fischer officially created the ghetto.
More than 10 miles (16km) of brick walls, up to 10ft (3m) high and topped with broken glass, had been built to segregate Warsaw's Jews.
Within a couple of months, almost 400,000 people were confined to an area roughly the size of New York's Central Park in appalling conditions. On average, seven people lived per room.
Strict food rationing led to starvation. Beggars became a common sight and children went bare foot in winter. Deadly typhus and TB epidemics broke out. On average, 4,000 people died each month.
At the time, Irena Sendlerowa was a 30-year-old nurse who worked for the city's health and care department. Since 1939 she had been taking enormous risks giving Jews food and shelter. The penalty for helping Jews in Nazi-occupied Poland was death. It was a threat that was often carried out.
But she recruited a group of her social worker colleagues to rescue children from the ghetto.
"I was brought up to believe that a person must be rescued when drowning, regardless of religion and nationality," she said.
Mrs Sendlerowa and a colleague, Irena Schultz, were allowed to enter the ghetto using special work passes. They smuggled children out in ambulances, through the sewers, or through a courthouse on the edge of the ghetto, which had a passage leading to the "Aryan" side.
In July 1942, the Nazis began the mass deportation of Warsaw's Jews to the Treblinka death camp in north east Poland. During that summer, 300,000 were murdered.
Persuading parents to part with their loved ones was particularly traumatic. Mrs Sendlerowa could give no guarantee the child would survive.
Jewish people in the ghetto rose up against the Nazis in 1943
"That was when we witnessed infernal scenes. Father agreed but mother didn't. Grandmother cuddled the child very tenderly and, weeping bitterly, said 'I won't give away my grandchild at any price'.
"We sometimes had to leave such unfortunate families without taking their children from them. I went there the next day to see what the whole building had come to and often found that everyone had been taken for transport to the death camps," she said.
The children were first taken to emergency safe houses, where they were taught basic Catholic rituals to pass as Poles until a family could be found to take them in.
"I once carried such a tearful, broken-hearted little boy to other guardians when he asked me, crying and sobbing, 'Please tell me how many mums can you have, for this is the third one I'm going to'," she said.
In December 1942, the Polish underground set up Zegota, the Council of Assistance for Jews. Mrs Sendlerowa became the head of its children's department. She had noted the names of all of the rescued children on cigarette papers and sealed them in two bottles.
In April 1943, several thousand of the remaining Jews in the ghetto rose up against the Germans. Armed with hand guns, grenades and home-made bomb launchers they held an SS brigade at bay for three weeks. By mid-May the ghetto was a giant field of rubble.
Mrs Sendlerowa continued her work, but on 20 October 1943, she was arrested at her home. She was taken to the notorious Gestapo headquarters in central Warsaw and tortured. During the sessions they broke her legs and feet but she refused to reveal any names.
"I still carry the marks on my body of what those 'German supermen' did to me then. I was sentenced to death," she said.
Zegota managed to foil the plan after they bribed a Polish-speaking German officer with a large backpack full of dollars. On the drive to her execution site the officer knocked her unconscious. He stopped the car and left her bleeding on the roadside.
"It is beyond description to tell you what you feel when travelling to your own execution and, at the last moment, you find you have been bought out," she said.
The following day, unaware the execution had not taken place, the German authorities put up posters all over the city announcing she had been shot. Mrs Sendlerowa read them herself.
She went into hiding and continued to work for Zegota. Several weeks later, her mother died. SS officers turned up at the funeral demanding to know where her daughter was.
On 1 August 1944, the Polish underground rose up against the Germans in the Warsaw Rising. As the street fighting raged Mrs Sendlerowa buried the bottles containing the children's names in a colleague's garden. Against overwhelming odds and precious little help from Poland's allies, the underground fought on for 63 days before finally capitulating.
When the Red Army liberated Warsaw in January 1945, she dug up the bottles and handed over the lists to the Jewish Committee. The information was used to return the hidden children to any surviving relatives.
One of the rescued was Elzbieta Ficowska, who now heads the Children of the Holocaust Association in Warsaw. As a five-month-old baby, she was smuggled out of the ghetto in a wooden tool box on a lorry carrying bricks.
"To me and many rescued children, Irena Sendlerowa is a third mother. Good, wise, kind, always accepting, she shares our happiness and worries. We drop in for Irena's advice when life presents us with difficulties," she said.
Another of those rescued was Michal Glowinski, now a literature professor.
"If being a saint is a complete devotion to a cause, bravery and altruism, then I think Mrs Sendlerowa fulfils all the conditions. I think about her the way you think about someone you owe your life to," he said.
But like many of the Righteous, Mrs Sendlerowa is modest about her achievements.
"Let me stress most emphatically that we who were rescuing children are not some kind of heroes. Indeed, that term irritates me greatly. The opposite is true. I continue to have pangs of conscience that I did so little," she said.