Initial work in the sector established a series of casemates in the Mormal Forest, well to the rear of Maubeuge. The casemates were built by the Commission d'Organisation des Régions Fortifiées (CORF), the Maginot Line's design and construction agency. At the same time, studies proceeded on the fortification of the exposed salients, or môles of Bavai and Maubeuge. As the fortification of the Maubeuge Front was commenced later than the main section of the Line to the east, funds were restricted by the impact of the Great Depression, which had reached France. A relatively ambitious project was nevertheless advanced, planning for five artillery ouvrages (Eth, Bavai, Quatre-Bras, L'Épine and Boussois) between Valenciennes and the Ardennes. The plan was progressively scaled back to four infantr