Poland had the largest Jewish population in Europe before World War II. There were 3,500,000 Jews living in the Second Republic, about 10% of the general population. Between the German invasion of Poland in 1939, and the end of World War II, over 90% of Polish Jewry perished. Nevertheless, more Jews were rescued by Catholic Poles, than in any other nation. According to Davies, the number of Jews saved by Poles is conservatively estimated at 100,000–150,000. The number of sheltered Jews according to Lukas was "as high as 450,000" at one time. Professor Tomasz Strzembosz put the total number of Catholic Poles saving Jews at 1 million. Among the 108 Martyrs of World War II beatified in 1999 by Pope John Paul II, prominent place belongs to religious people murdered by Nazi Germany for saving Jews. Several hundred Christian Poles were summarily shot in open pits for sheltering Jews in the vicinity of the Słonim Ghetto along with their priest, . Sisters of the Immaculate Conception of the Blessed Virgin Mary were arrested and executed the following day for hiding Jewish children in their convent. , the superior of the convent, and , a doctor, were beatified by Pope John Paul II together with priest Adam Sztark. They were killed at the same time. In 2001, Sztark became the first Jesuit ever awarded the title of Righteous Among the Nations by the state of Israel. He used to deliver food to the ghetto, purchased with cash donations from his parishioners. He also issued false certificates, personally sheltered Jewish refugees, and called upon all his congregation to help to save the ghetto residents.