Einstein, who was Jewish, was undertaking a visiting professorship at the California Institute of Technology in Pasadena when Adolf Hitler was appointed Chancellor on 30 January 1933. With the Nazis expanding their power in Germany, Einstein chose not to go home when he returned to Europe in March. When his ship docked at the Belgian port of Antwerp on 28 March he renounced his German citizenship by handing in his passport at the German Consulate.
While the Nazis seized Einstein’s cottage and converted it to a Hitler Youth camp, the government barred Jews from teaching at universities and the German Student Union burned his books. With a bounty on his head, Einstein stayed in Belgium for a few months before moving to Britain where he was guarded by his friend, naval officer Commander Oliver Locker-Lampson.
While a refugee in Britain, Einstein lobbied foreign governments and universities to find employment for former German Jewish scientists. Many places were found around Europe, with over 1,000 German Jewish scientists being placed in Turkish universities alone, but Einstein himself was refused British citizenship and instead accepted an offer from the Princeton Institute for Advanced Study in New Jersey. He departed England on 17 October 1933.
Although Einstein initially intended to only stay in the United States for a short time, in 1935 he chose to seek American citizenship, which he gained in 1940. By this time he had warned President Roosevelt about the danger of Hitler developing nuclear weapons, and encouraged the United States to begin its own research.