If the reader should wonder why a low ridge of this kind could prove an obstacle to the advance of armies, and should be thought even in so desperate a case worthy of defence, the explanation is this: armies depend for their very lives, and equally for their offensive power, upon a train of vehicles and guns. They are tied to roads. And such a feature as the Argonne, low though it be, dense with wood and undergrowth, and built of deep, damp clay, was almost as effectual a barrier to invasion as might be an equally broad arm of water. The few roads across it, cut through the woods and hardened, in particular the great Paris road from Germany which crossed it at the point called “les Islettes,” are like bridges or causeways over such an arm of water, and as necessary for the passage of any army as are bridges over water. To hold these passes, if it were possible, was all Dumouriez’s plan. For Verdun had fallen in the first days of this month of September (1792), more than half of which had now run in that week when Dumouriez lay along the hillside with his men, every pass guarded, and awaiting the shock. That shock came in the form of direct assaults upon the roads across the hills, attempts to carry them with the high hand. These assaults at first failed. An enemy attempting thus to break some link in a chain of defence will make for the weakest. If Prussia and Austria were to cross the Argonne, it must be by that one of the four roads where the resistance was weakest. The direct road, the great Paris road, which was the southernmost of the four passages, they would not first attempt. They managed in their second effort to break the line at that point called “The Cross in the Woods,” a day’s march to the north. They lost but few men in this success. They gained their gate; Dumouriez’s line was pierced. Hurriedly in the night he withdrew all those of his men who, lying to the north, would have been isolated had they waited for the dawn, and he fell back down the hills, standing now with his back to Germany, his face to Paris, and knowing that his position was turned. For though the Paris road was still held, the enemy was pouring round through the breach in the dyke above, and the way to the capital was open for the enemy round by that northern road. All the weather of those few days had been drenching rain. The clay of the hills was sodden, the autumn leaves drifting upon it throughout the forest; the bare, rolling plains and the chalk were sodden with it, too. It was the nineteenth of September, and Kellermann, just in time by a few hours, but with reinforcements that could hardly save his country, had effected his junction with his chief. So Dumouriez, with Kellermann now linked on to him to his left and to the south, stood with his back to the Argonne and his face to Paris, waiting for inevitable catastrophe, while round by his right hand the enemy poured through into the open plain.