With the Anschluss, Germany's annexation of Austria on 12 March 1938, Meitner lost her Austrian citizenship. Niels Bohr extended an offer to lecture in Copenhagen, and Paul Scherrer invited her to attend a congress in Switzerland, with all expenses paid. Carl Bosch still said that she could remain at the KWI for Chemistry, but by May she was aware that the Reich Ministry of Science, Education and Culture was looking into her case. On 9 May, she decided to accept Bohr's invitation to go to Copenhagen, where Frisch worked, but when she went to the Danish consulate to get a travel visa, she was told that Denmark no longer recognised her Austrian passport as valid. She could not leave for Denmark, Switzerland or any other country.