A "blockhaus" is a small bunker with only a few embrasures. They are small observations posts, outpost or build in places witch are less defended. The armament is a machine gun or a light anti-tank gun

During the period of 1939 - 1940 the MOM (M.O.M. = Main Oeuve Militaire) has build a lot of small bunkers to defend the holes in the line. The M.O.M bunkers are build by the soldiers supported by the engineers