During the Occupation, the premises had already been requisitioned by the German army to house a hospital belonging to the 617th Field Hospital. This unit had been based in Arras, Lille and Lens since the invasion of May 1940. With a capacity of 1,000 beds, it was refocused on the Franco-Belgian border in February 1942. The headquarters remained in Lille, while its branches moved to Jemappes, Ghent and Cambrai.