Through the transverse gap from Rheims to Berry-au-Bac on the Aisne there is one of those wonderful old Roman roads, now a great modern highway. The road runs nearly straight as a ruler north-west to Laon. The first step taken by General Desperey was to secure this road, as well as the railway which on the western side of the gap winds curiously in and out along the foot of the hills. From Berry-au-Bac north of the Aisne the French lent most material aid to the British attack upon Craonne. South-east of Rheims they were occupied in securing the railway to Chalons, which for some twenty miles runs through the valley of the Vesle. Above Rheims this valley, in character not unlike the valley of the Aisne, but wilder, may be compared to a great crack in the plateau of the highlands. On each side are chalk cliffs, and side valleys of gravel soil covered with woods. Between the cliffs the river winds through flat meadows. Towards Rheims the valley opens out into that theatre of wooded hills in the midst of which the city is situated. The operations of this part of the great battle resolved themselves partly into a struggle for the transverse gap; next into a gigantic combat waged from opposite sides of the theatre of hills; and lastly, into a fight for command of the upper valley of the Vesle. Sheltered among the caves and quarries on the north-east side of the gap and of the theatre of hills, the Germans had contrived a scheme of defence works not less elaborate than those along the ridge north of the Aisne, and these defence works extended round the theatre of hills to the outlet from the narrow part of the Vesle valley, blockading both the main military road from Rheims to Chalons, and also the railway. At the outset their reduced strength limited them to merely defensive tactics, and, as on the north of the Aisne, they steadily, and day by day, lost ground. But they then began steadily and day by day to receive reinforcements, both of men and of heavy artillery. The reinforcements of men included a reconstitution of the Prussian Guard drawn from its reserves at Berlin. Before the end of September an immense body of additional troops had arrived at this part of the front. On the side of the French, also, strong reserves were hurried forward. It will assist to understand the description of the operations to state first their plan and purpose both on the one side and the other, since this formed strategically the critical section of the battle. At Condé-sur-Aisne, it will be recalled, the Germans held a position right on the river, and that position formed a wedge or salient jutting into the British lines east and west of it.