Errard de Bar-le-Duc made use of the ancient walls, considering them suitable for defence at close quarters; but he constructed works outside which would command the country, and force the besieger to commence his operations at a distance of one thousand or one thousand two hundred yards. The system of boulevards was still maintained, but these, instead of presenting only an isolated obstacle, defended each other by crossing their fire, and were, in fact, true bastions. [Illustration: FIG. 59.--THE BASTIONS OF ERRARD DE BAR-LE-DUC.] The three great round towers on the north of the _cité_ of La Roche-Pont were then much dilapidated. Errard had them terraced, and then surrounded them with earthworks with walled escarpments. Towards the plateau fronting the north he had a great tenaille constructed with a double ditch and ravelin. Fig. 59 gives the plan of the _cité_ after the operations planned by Errard. Besides the works just mentioned, indicated at A, B, C and D, the king's engineer raised the bastions, E, F, G, H, and I, which crossed their fires, and whose orillons masked small pieces designed to flank the old ramparts. Most of the old towers were lowered and terraced to receive cannon. The ancient castle, of which little more than the donjon and some outbuildings remained, was surrounded by a bastioned enclosure, with a tenaille on the town side. The lower town, towards the west, though reduced to narrow dimensions, continued nearly in the condition already described. As to the upper town, after the conflagration of the last siege, it had been rebuilt in a very indifferent style. Under Francis I., the abbey had been secularised, and its ancient church was served by a Chapter. The old stone bridge near the outflow of the rivulet still existed, and at O was a second wooden bridge connecting the two shores. The bridge, P, had fallen into ruins and had not been rebuilt. [Illustration: FIG. 60.] From the bastion, B, to the river, and from the bastion, D, to the pool, Errard built two fronts, K and L, _à crémaillères_,[50] to command the slopes of the plateau on the right and left, and to hinder an assailant from occupying a position on the east and west flanks of the _cité_.