Emile Borel's difficult days in 1941

The German forces occupying Paris arrested Emile Borel and three other members of the Acad'emie des Sciences in October 1941 and released them about five weeks later. Why? We examine some relevant German and French archives and other sources and propose some hypotheses. In the process, we review how the Occupation was structured and how it dealt with French higher education and some French mathematicians.