A deep ditch partly cut in the rock separated the stronghold from the Némède. The defences consisted of an enclosure, made in Gallic fashion, of trunks of trees alternating with layers of stone surmounted by wattling. A large quadrangular tower, constructed in the same way, enclosing four stories, and terminated by a roof of reeds covering a crenelation, served as a place of retreat. Within the enclosure were wooden huts for the garrison; as the tower, which was only twenty paces wide by twenty deep, and whose walls were thick (about three paces), could barely contain a hundred men. Titurius reconnoitred the approaches. The ditch interrupted all communication with the Oppidum, and ended against its ramparts. Towards the south, the stronghold rose immediately over the escarpment, which on this side was so steep that no ditch had been required. But a palisade on the outside, fixed in a mound, prevented approach to the base of the stronghold. As stated before, the walls of the upper town occupying the southern slopes extended to the rampart of the Oppidum. But these walls had been abandoned by the warriors of Catognatus who had taken refuge in the stronghold. On quitting the upper town they had set fire to the bridge, seeing which, the Romans posted opposite the head of the bridge had passed this latter without meeting any resistance, and had succeeded in extinguishing the flames. The bridge was promptly repaired. The legate, therefore, effected a communication with his troops in the northern quarter, who were then occupying the upper town, and completely invested the stronghold. Time pressed, and as he had already lost twelve days before the Oppidum, haste was necessary. In the first place, he sent one of the Gallic prisoners to hold a parley with the defenders of the stronghold. He promised to spare their lives if they would give up their chief, and the Helvetii that might be among them. If, on the other hand, the attack was once commenced, they must expect to be all put to the sword. The messenger was received by a shower of stones, and returned bleeding to the legate, who could no longer hesitate. The order was given to fill up the ditch, and to speed the work; the centurions, employing threats and blows at need, compelled a good many of the vanquished to carry faggots and earth. Protecting themselves with mantelets, the Romans suffered only trifling loss, for the besieged had but few missiles. Besides, Titurius had brought up the engines of war, demolished those parts of the wall of the Némède which might embarrass the operations, and posted the best slingers and archers on the flanks, so that the rampart of the stronghold, riddled with projectiles, was scarcely tenable. At night the filling-in of the fosse was consolidated by timberwork, on which were spread brushwood and turf. At the first hour of the day a cohort advanced in slow march on the ground thus made, forming the _testudo_ (Fig. 13). [Illustration: FIG. 13]