After the war of 1870-71, when the French began building fortresses to guard their eastern frontier, they arranged that if the enemy should capture Montmédy, Mezières, Hirson, Maubeuge, and Lille, as they had now done, a stand was to be made for the defence of Paris along an undulating plateau of chalk which rises gently from the valley of the Marne, but falls steeply on the north-east to the plains of Northern France. These uplands, as seen from the north, resemble the Surrey and Sussex Downs, and are known as the Heights of Champagne. On them grow the grapes which make the sparkling wine known as champagne. Several streams, the largest of which is the Aisne,[70] cut their way through the plateau; stumps of trees and belts of woodland are common, and on the western side towards the Oise there are wide stretches of forest. [Illustration: The French Army in the Champagne Country. _Photo, Farringdon Photo Co._] The little map on the opposite page will help you to understand the defensive character of the Heights of Champagne. Notice the two towns which were fortified to defend the scarp of the heights against attack from the north and north-east--La Fère,[71] on the Oise, an entrenched camp, with a circle of forts on both sides of the river; and Laon,[72] an old city built on a long spur which encloses a remarkable V-shaped valley, partly wooded and partly covered with gardens and vineyards. The carriage road to the upper town of Laon ascends in curves from near the station, but foot passengers may climb to it by means of a stairway of 260 steps and a series of inclined planes. On the highest part of the hill stands the ancient citadel, and towering above its ramparts are the bold and graceful towers of a beautiful cathedral. The forts erected round this city were so placed that their fire crossed that of the forts at La Fère. Lines of defence extended along the steep north-eastern face of the plateau, and also along its eastern side to the valley of the Aisne. Beyond the Aisne valley the eastern system of defences was continued to the valley of the Marne. About midway between the two rivers, but to the east of the plateau, is the fortress of Rheims,[73] one of the most interesting cities of France, and the chief centre of the trade in champagne. Rheims stands on the plain, and behind it rise the vine-clad uplands. In front of it is the bold wooded hill known as the Mountain of Rheims. This hill, at the time of which we are speaking, was strongly fortified. [Illustration: Sketch of Defensive Line of the Heights of Champagne.] Such was the position chosen in 1874 as the great line of defence against an army advancing on Paris. While the French retreat was in progress, many persons in this country thought that a great stand would be sure to be made in this region; but, to their surprise, the French continued their southward march.