Beyond the Rheims–Epernay wine district and the St. Gond Marshes (source of the Petit Morin), we pass into the great expanse of the Champagne moorlands, poor and thinly populated, where large tracts of chalk soil carry nothing but plantations of stunted pines and firs. Châlons-sur-Marne, its capital, has a large permanent garrison, with fixed camps and manœuvre grounds hard by. Vitry-le-François, at the junction of the Saulx and Ornain with the Marne, and of the Paris–Nancy and Châlons–Rheims railways, is the only other considerable town. On the west of this region, Foch held against Bülow and the Saxons; on the east occurred the shock of de Langle’s army with that of the Duke of Würtemberg. Finally, beyond Revigny, the forces of General Sarrail and the Imperial Crown Prince fought across a more composite region, consisting, in the south, of the Barrois——the district of Bar-le-Duc——and, to the north of this, the near part of the thickly-wooded Argonne hills, the Verdun Heights, and the plain between. Verdun was and remained a defensive position worthy of its ancient renown; and the Argonne, with Valmy on one flank and Varennes on the other (to cite only two historic names), has always been a barrier against invasion secondary to the Heights of the Meuse. These latter are continued with only small breaks by the Heights of the Moselle, where, especially on the hills near Nancy, took place the coincident struggle by which the eastern defence line was preserved. While this must be borne in mind, as an essential part of the general French victory, it seems legitimate and convenient to treat it separately; a brief recital of what there occurred is, accordingly, postponed to the end of our narrative. The military geographer will have much to add to this note of the lie of the land. He will be able to show that all the natural features of the country affected the result; the rivers of the western area inconveniencing both sides, but especially the invader; the patches of forest and the direction of highroads limiting their movements; the French gaining from a virtual monopoly of railway services a power of rapid transfer of troops that was one of the decisive factors of the battle. Everywhere, hill positions proved to be of great tactical value; and this is supremely true of the eastern ranges. The Argonne block delayed and split the Crown Prince’s columns, and so greatly helped Sarrail to maintain his line. The Upper Meuse and its earthy rampart were a still more precious protection. Between Verdun and Nancy, a distance of 60 miles, only one point was attacked, in the crisis, and this was held by a single fort, that of Troyon. Yet another hill range has signally aided the enemy in the end of the battle, when the victorious Allies were brought up sharp against the Laon Mountains, north of the Aisne. Throughout the field, superior knowledge of the ground must be counted among the advantages of the French.