In 1939, Hitler invaded Poland, beginning World War II. Poland was mostly Catholic. The Nazis wanted to destroy Poland. They started by destroying the Catholic Church in Poland. They arrested the Church's leaders and closed churches and monasteries. In 1940, the Nazis created a special barracks just for priests at Dachau concentration camp. Of 2,720 clergy imprisoned at Dachau, almost all (94.88 percent) were Catholic. About 1,700 were Polish priests; half of them died or were killed at Dachau. The Nazis even made it illegal for priests anywhere to give Catholic sacraments to Polish people. At least one German priest was sent to Dachau for taking a confession from a Polish Catholic.