factor of the
battles of the Marne was the topographical factor, the consideration of
the land over which the action was to take place.

Let the River Marne be used as a base from which this topography can be
determined. The Marne rises near Langres, which is the northwest angle
of that pentagon of fortresses (Belfort, Epinal, Langres, Dijon, and
Besancon), which incloses an almost impregnable recuperative ground for
exhausted armies. From Langres the Marne flows almost north by west for
about fifty miles through a hilly and wooded country, then, taking a
more westerly course, it flows for approximately seventy-five miles
almost northwest, across the Plain of Champagne, past Vitry-le-Francois
and Chalons, thence almost due westward through the Plateau of Sezanne,
by Epernay, Chateau Thierry, La Ferte-sous-Jouarre, and Meaux to join
the Seine just south of Paris. In the neighborhood of Meaux, three small
tributaries flow into the Marne--the Ourcq from the north, and the Grand
Morin and Petit Morin from the east. The Marshes of St. Gond, ten miles
long from east to west and a couple of miles across, lie toward the
eastern borders of the Plateau of Sezanne, and form the source of the
Petit Morin, which has been deepened in the reclamation of the marsh
country.

Once more considering the source of the Marne, near Langres, it will be
noted that the River Meuse rises near by, flowing north by east to Toul,
and then north-northwest past Verdun to Sedan, where it turns due north,
flowing through the Ardennes country to Namur, in Belgium. To the east
of the Meuse lies the difficult forest clad hill barrier, known as the
Hills of the Meuse; to the east extends (as far as Triaucourt) the
craggy and broken wooded country of the Argonne, a natural barrier which
stretches southward in a chain of lakes and forests.

West of this impassible country of the Meuse and the Argonne lies the
plain of Champagne-Pouilleuse, which is almost a steppe, bare and open,
only slightly undulating, overgrown with heath, and studded here and
there by small copses of planted firs, naught but a small portion of the
whole being under cultivation. Between the Forest of the Argonne and
this great plain, which is over a hundred miles long from north to south
and forty miles in width, lies a short stretch of miniature foothills,
with upland meadows here and there, but crossed in every direction by
small ravines filled with shrubs and low second-growth timbe