Before dealing with those new German tactics, it is advisable briefly to sketch the defence works thrown up by the Germans along their line, [Pg 100]because both these defence works and the character of the country are intimately related to the tactics.

As already stated, the highlands of Champagne extend north-west nearly as far as Peronne. They are chalk hills and uplands cut by deep valleys. The most northerly of the valleys is that out of which flows the Somme. Then comes the much wider valley of the Oise. Still farther south is the valley of the Aisne. Between the Oise and the Aisne is a roughly triangular tract of country, its apex at the point where the Oise and the Aisne join. Across the broad end or base of this triangle run the open downs. Towards the narrower end of the area the country becomes broken and hilly, 일산오피 and is covered with great patches of wood and forest.

There is along the north of the Aisne a long wooded ridge, which on its northern edge slopes steeply. But the top of the ridge forms a gentle undulating slope to the south. It is not unlike the top of a rough, slightly tilted table. To a bird's-eye view this top would appear shaped rather like a very coarse-toothed comb, with the teeth jagged and broken. The top, that is to say, runs out on its south side into a succession of promontories, each ending in a round-ended bluff overlooking the Aisne valley. Some of these bluffs jut out close above the river. Others are much farther back. Between them are clefts and side valleys, in which the land slopes up from the bottom of the main valley to the top of the plateau. In the longer clefts, of course, the general gradient is much less stiff than in the[Pg 101] shorter ones. Both the tops of the bluffs and most of the clefts are thickly wooded. The bluffs are on an average above 400 feet in height, that in fact being the general elevation of the plateau.