Bohr returned to the University of Copenhagen as a professor of physics in 1921. With the help of the government and the Carlsberg Beer Foundation he established the Institute of Theoretical Physics. Bohr’s Institute attracted all the major theoretical physicists from around the world for short visits or extended appointments. When the Germans occupied Denmark, Bohr made a daring escape, first to Sweden, then England, then the United States. He was a consultant in the atomic bomb development effort, but after the war he tried to get President Harry Truman (1884-1972) and British leader Winston Churchill (1874-1965) to agree to share the secrets of the bomb with all countries, including the Soviet Union. They both rejected Bohr’s proposal. But after the Soviets developed the bomb, Bohr’s ideas helped found the United Nations’ International Atomic Energy Agency. Until his death in 1962 he worked to reduce the threat of a nuclear war. In the centenary of his birth Denmark issued a postal stamp showing Bohr and his wife, Margarethe.