The Fortified Region of Metz comprised the central and most heavily fortified portion of the Maginot Line. The region was established in 1926 as a military organization for the French fortifications along the frontier with Luxembourg and Germany to the east of Longuyon in northeastern France, forming a shield to the north of the industrialized areas of Metz and Thionville. The region was dissolved as a military organization on 18 March 1940, its command personnel moving to the 42nd Army Corps. The region was divided into four sectors: