[Sidenote:  The terrain beyond is less rugged.]

Immediately beyond, the terrain is not so difficult.  The Clignon valley becomes less rugged and gradually blends with the plateau.  Toward Bezu-St.-Germain and Epieds lies a comparatively open plain with extensive stretches of fallow land.  In this more open region the progress was more rapid; on July 22 the American troops took possession of Epieds, twelve kilometres from Bouresches, their starting point.

[Sidenote:  Along the valley of the Ourcq.]

But the difficulties are more serious farther to the north, along the hills which form the southern boundary of the valley of the Ourcq.  Although the depression made by the Ru d’Alland, being broad and level, is not a considerable obstacle, it is not the same beyond.  The relief map shows a line of heights running from west to east, and rising higher and higher in that direction.  From these heights a multitude of valleys descend to the Ourcq, from south to north, cutting the crest into hills separated by depressions.  Thus the terrain is broken up in every direction and well adapted to meet an attack from the west as well as one from the south.

[Sidenote:  The French carry ridges and valleys in succession.]

It was necessary to deal with all these obstacles one by one.  Starting from the west, the French had to carry successively these lines of crests and depressions with their fortified villages:  ridge of Monnes, July 19; ravine of Neuilly-St-Front the same evening; the hill of Latilly and its wood the 20th; La Croix and Grisolles the 21st, with their thickets and dense plantations of osiers.  On the 23d the Allied troops took Rocourt and the wood of Le Chatelet; on the 24th the deep ravine of Brecy; and, finally, on the 25th, French and Americans together attacked the hill of the forest of Fere, which is 228 metres high, completely covered with woods, cut by ravines, and flanked by fortified villages.  On the 27th the whole position was taken, and the Allies were on the verge of the deep valley of the Ourcq, which they were next to cross.

[Sidenote:  Caves in the cliffs.]

[Sidenote:  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 Fere-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, Breny, Armentieres,—­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.