German troops crossing into Luxembourg through the Schuster Line
On the 10th of May 1940, the Wehrmacht forcibly occupied Luxembourg. The government and the grand duchess fled to their exile of London. After initial military administration, a civilian one under Gustav Simon, NSDAP Gauleiter of nearby Moselland, was implemented. Luxembourgians were drafted by the Wehrmacht and for military service, and Jewish citizens deported to German concentration camps. The country wasn't formally annexed, though.
On May 17th, in Luxembourg City the Volksdeutsche Bewegung was founded, lead by Damian Kratzenberg. Its main purpose was making Propaganda to move the Luxembourgians to a more pro-German position, to lead them „heim ins Reich“ (back into...).