Allies turn the line of the Ourcq.
This line was a by no means inconsiderable obstacle. Imagine, if you please, a deep depression, twisting and turning in all directions, and from 200 to 400 metres wide, extending at least as far as Fère-en-Tardenois. It is bounded on either side by cliffs of hard limestone, 30 to 40 metres high, in which innumerable caves are scooped—the so-called boves, which are used as dwellings, with doors and windows flush with the face of the cliff. These boves are invaluable defensive positions, out of reach of bullets and shells. The valley bottom is wet and swampy, with dense clumps of poplars mingled with alder-bushes. There are numerous villages at the foot of the cliffs,—Rozet-St.-Albain, Brény, Armentières,—or on the slopes above, like Noroy. A frontal attack on such a position would have been too costly. The Allies turned the line of the Ourcq from the north. They crossed the river in force in the upper part of its course, where it has not yet attacked the stratum of hard limestone, and where the valley is wider, and the sides are less steep. Nevertheless they encountered terrible difficulties.
Strategic value of hills of Orxois.
North of the Ourcq, indeed, the last heights of the Orxois form another chain of hills, from four to six kilometres wide—the last obstacle before we come to the plateau of the Soissonnais. These hills are of the greatest possible diversity of shape and vary in height from 200 metres at the western extremity to 230 at the eastern. Their bases consist largely of sandstone and Fontainebleau sand, with clumps of forest scattered here and there; higher up is the softer limestone, the land being entirely cleared and covered with crops. Here and there we find the remains of the former covering of clay and Fontainebleau sand—wooded ridges which expand toward the east into the wood of Seringes, the forest of Nesle, and Meunière wood. These hills, the last as we travel northward, where they command the whole of the Soissonnais, have therefore the greatest strategic value, particularly the positions of Hartennes, Plessier-Huleu, and Seringes.
The French approach from the west.
Luckily these formidable defensive positions were approached from the west, astride the ridges. Starting from the forest of Retz, the French crossed the Savières with a rush, and in a single bound reached Noroy-sur-Ourcq and Villers-Hélon, which lie along one of the ridges, surrounded by orchards. On July 19 they had advanced three kilometres to the east; the strong line of the Ourcq was outflanked. On the 20th they were at Parcy-Tigny and Rozet-St.-Albain, pushing forward over the broken ground planted with sugar-beets and cereals, enlivened in spots by small clumps of trees perched on the sandstone hillocks. Thus they drew near to the heart of the position—the ridges of Plessier and of Hartennes. There the resistance was much more violent; but after three days of hard fighting, the French entered Plessier and approached the village of Oulchy-la-Ville, surrounded by picturesque heaps of sandstone blocks mingled with pines and birches. On the 25th, in the evening, they were in occupation of Oulchy-le-Château, which lies in a charming vale running down to the Ourcq. The line of the Ourcq, as to that portion where the river, flowing between high cliffs, constitutes a real obstacle, was in the Allies' hands.
Fère-en-Tardenois and Sergy.
It remained to complete the victory by the conquest of the eastern sector of the hills; and this again was no easy task. The French and Americans had now to approach that strong defensive position from the south. On the 28th they entered Fère-en-Tardenois; the Americans crossed the Ourcq, taking Sergy, which changed hands nine times. On July 31, after more titanic battles, they wrested Seringes from the foe. On August 1 there was a general advance all along the line, and the Allies carried the whole line of hilltops, from Plessier-Huleu to Meunière wood.
Heroes of the second battle of the Marne.
This was the end: the horizon expanded. From the heights conquered in fourteen days of fighting the Allies went down to the plateau of the Soissonnais; soon they would reach the Vesle and join hands with the troops who had retaken Soissons. Among the numberless heroes of this second battle of the Marne, they who stormed the heights of the Orxois and either outflanked or crossed the valley of the Ourcq were the bravest of the brave and are entitled to the largest share of our gratitude. The third act of the battle was played upon a terrain quite different from those preceding it. The relief is considerably simplified. The great plateau of the Ile de France, which is buried, as it were, under the accumulations of recent deposits, where erosion has worn gaps in the ridges of the Orxois, and hollowed out the deep ravines of the Tardenois, is reduced here to the substratum of hard limestone, almost entirely free from superimposed layers. So that, instead of being an uneven, swampy district, the Soissonnais is a dry level table-land, where the streams flow underground through the layers of limestone. A fertile district, too, for the surface is covered with a thin coating of loam, in which sugar-beets and cereals vie with one another in profusion of growth.