The attachment of the departments Nord and Pas-de-Calais to the military administration in Brussels was initially made on military considerations, and was supposedly done in preparation for the planned invasion of Britain.[7] Ultimately, the attachment was based on Hitler's intention to move the Reich's border westward, and was also used to maintain pressure on the Vichy regime - which protested the curtailment of its authority in what was still de jure national French territory - to ensure its good behavior.[8]