Fort de la Malmaison lay on the Chemin-des-Dames ridge and had been built as part of an entrenched camp north of the Aisne, in the Séré de Rivières system, designed by General Raymond Adolphe Séré de Rivières and built from the 1870s.
The fort was in the northern angle between the Chemin-des-Dames and the Soissons–Laon road.
The fortress casemates were tested with high explosives in 1887 and found to be insufficiently robust.
Steel reinforced concrete had been added but in 1913, the fort was sold to a Laon contractor, to demolish and use the materials to build new barracks in town.
A long tunnel, the Montparnasse Quarry lay on the northern slopes below the fort, on the route to Chavignon village at the foot of the ridge.
The quarry was big enough to shelter an infantry brigade.
The fort was to the north-west of the quarry, on the summit of the plateau at the western end of the ridge and the dismantled work was surrounded by a moat filled with mud.
The subterranean galleries had been rebuilt and garrisoned by the Germans in September 1914, the outworks and interior being provided with several ferro-concrete machine-gun nests.

From the ramparts, the Germans could see all movement from the Ailette to the Aisne and on the spurs running down to the Aisne from the Chemin-des-Dames ridge.
There was a clear view northwards from the fort over the Ailette, along the lower edge of the west side of the Forest of Coucy and past the village of Brancourt; to the east were two groups of hills round Anizy, on the north bank of the Ailette.
Laon was about 13 km (8 mi) distant and visible at the end of the valley of the Ardon, which joins the Ailette north of Chavignon.
Further east, beyond the Bassin d'alimentation reservoir, was the hilltop village of Monampteuil.
East of the reservoir, the valley of the Upper Ailette was visible as far as the Troyon–Laon road.
South of Fort de la Malmaison, in the centre of the plateau closer to the French lines, lay the huge Bohery Quarry, where the ground began to slope steeply down towards the Aisne valley.
In October 1917, German engineers were still connecting the quarry with the Montparnasse tunnel, other underground works and the galleries under the fort.
The Montparnasse, Fort de la Malmaison and Bohery excavations, the Fruty Quarry on the edge of the Soissons–Laon road, about 1.6 km (1 mi) east of Laffaux Mill and many other subterranean obstacles faced the Sixth Army.
Fort de la Malmaison lay on the Chemin-des-Dames ridge and had been built as part of an entrenched camp north of the Aisne, in the Séré de Rivières system, designed by General Raymond Adolphe Séré de Rivières and built from the 1870s. The fort was in the northern angle between the Chemin-des-Dames and the Soissons–Laon road. The fortress casemates were tested with high explosives in 1887 and found to be insufficiently robust. Steel reinforced concrete had been added but in 1913, the fort was sold to a Laon contractor, to demolish and use the materials to build new barracks in town. A long tunnel, the Montparnasse Quarry lay on the northern slopes below the fort, on the route to Chavignon village at the foot of the ridge. The quarry was big enough to shelter an infantry brigade. The fort was to the north-west of the quarry, on the summit of the plateau at the western end of the ridge and the dismantled work was surrounded by a moat filled with mud. The subterranean galleries had been rebuilt and garrisoned by the Germans in September 1914, the outworks and interior being provided with several ferro-concrete machine-gun nests.
From the ramparts, the Germans could see all movement from the Ailette to the Aisne and on the spurs running down to the Aisne from the Chemin-des-Dames ridge. There was a clear view northwards from the fort over the Ailette, along the lower edge of the west side of the Forest of Coucy and past the village of Brancourt; to the east were two groups of hills round Anizy, on the north bank of the Ailette. Laon was about 13 km (8 mi) distant and visible at the end of the valley of the Ardon, which joins the Ailette north of Chavignon. Further east, beyond the Bassin d'alimentation reservoir, was the hilltop village of Monampteuil. East of the reservoir, the valley of the Upper Ailette was visible as far as the Troyon–Laon road. South of Fort de la Malmaison, in the centre of the plateau closer to the French lines, lay the huge Bohery Quarry, where the ground began to slope steeply down towards the Aisne valley. In October 1917, German engineers were still connecting the quarry with the Montparnasse tunnel, other underground works and the galleries under the fort. The Montparnasse, Fort de la Malmaison and Bohery excavations, the Fruty Quarry on the edge of the Soissons–Laon road, about 1.6 km (1 mi) east of Laffaux Mill and many other subterranean obstacles faced the Sixth Army.
Battle of La Malmaison