The Fortified Sector of Flanders (Secteur Fortifié des Flandres) was the French military organization that in 1940 controlled the section of the French border with Belgium between Lille and the North Sea.
In the case of the Flanders sector, no large fortifications of the kind typified by the Maginot Line were built in the area.
Fortifications were confined to almost two hundred blockhouses built during the 1930s, and some defensive inundations in the vicinity of Dunkirk.
Scattered among the smaller blockhouses were more elaborate blockhouses termed "positions of resistance", designed either by local forces or by the Service Technique du Génie (STG), the French Army engineering corps.
It consisted of eight STG casemates, whose armament (a GFM cloche), was never installed.