He arrived (607) in Utica at a moment when much was at stake. The Roman admiral Mancinus, charged by Piso with the nominal continuance of the siege of the capital, had occupied a steep cliff, far remote from the inhabited district and scarcely defended, on the almost inaccessible seaward side of the suburb of Magalia, and had united nearly his whole not very numerous force there, in the hope of being able to penetrate thence into the outer town. In fact the assailants had been for a moment within its gates and the camp- followers had flocked forward in a body in the hope of spoil, when they were again driven back to the cliff and, being without supplies and almost cut off, were in the greatest danger. Scipio found matters in that position. He had hardly arrived when he despatched the troops which he had brought with him and the militia of Utica by sea to the threatened point, and succeeded in saving its garrison and holding the cliff itself. After this danger was averted, the general proceeded to the camp of Piso to take over the army and bring it back to Carthage. Hasdrubal and Bithyas availed themselves of his absence to move their camp immediately up to the city, and to renew the attack on the garrison of the cliff before Magalia; but even now Scipio appeared with the vanguard of the main army in sufficient time to afford assistance to the post. Then the siege began afresh and more earnestly. First of all Scipio cleared the camp of the mass of camp-followers and sutlers and once more tightened the relaxed reins of discipline. Military operations were soon resumed with increased vigour. In an attack by night on the suburb the Romans succeeded in passing from a tower--placed in front of the walls and equal to them in height--on to the battlements, and opened a little gate through which the whole army entered. The Carthaginians abandoned the suburb and their camp before the gates, and gave the chief command of the garrison of the city, amounting to 30,000 men, to Hasdrubal. The new commander displayed his energy in the first instance by giving orders that all the Roman prisoners should be brought to the battlements and, after undergoing cruel tortures, should be thrown over before the eyes of the besieging army; and, when voices were raised in disapproval of the act, a reign of terror was introduced with reference to the citizens also. Scipio, meanwhile, after having confined the besieged to the city itself, sought totally to cut off their intercourse with the outer world. He took up his head-quarters on the ridge by which the Carthaginian peninsula was connected with the mainland, and, notwithstanding the various attempts of the Carthaginians to disturb his operations, constructed a great camp across the whole breadth of the isthmus, which completely blockaded the city from the landward side. Nevertheless ships with provisions still ran into the harbour, partly bold merchantmen allured by the great gain, partly vessels of Bithyas, who availed himself of every favourable wind to convey supplies to the city from Nepheris at the end of the lake of Tunes; whatever might now be the sufferings of the citizens, the garrison was still sufficiently provided for. Scipio therefore constructed a stone mole, 96 feet broad, running from the tongue of land between the lake and gulf into the latter, so as thus to close the mouth of the harbour. The city seemed lost, when the success of this undertaking, which was at first ridiculed by the Carthaginians as impracticable, became evident. But one surprise was balanced by another. While the Roman labourers were constructing the mole, work was going forward night and day for two months in the Carthaginian harbour, without even the deserters being able to tell what were the designs of the besieged. All of a sudden, just as the Romans had completed the bar across the entrance to the harbour, fifty Carthaginian triremes and a number of boats and skiffs sailed forth from that same harbour into the gulf--while the enemy were closing the old mouth of the harbour towards the south, the Carthaginians had by means of a canal formed in an easterly direction procured for themselves a new outlet, which owing to the depth of the sea at that spot could not possibly be closed. Had the Carthaginians, instead of resting content with a mere demonstration, thrown themselves at once and resolutely on the half-dismantled and wholly unprepared Roman fleet, it must have been lost; when they returned on the third day to give the naval battle, they found the Romans in readiness. The conflict came off without decisive result; but on their return the Carthaginian vessels so ran foul of each other in and before the entrance of the harbour, that the damage thus occasioned was equivalent to a defeat. Scipio now directed his attacks against the outer quay, which lay outside of the city walls and was only protected for the exigency by an earthen rampart of recent construction. The machines were stationed on the tongue of land, and a breach was easily made; but with unexampled intrepidity the Carthaginians, wading through the shallows, assailed the besieging implements, chased away the covering force which ran off in such a manner that Scipio was obliged to make his own troopers cut them down, and destroyed the machines. In this way they gained time to close the breach. Scipio, however, again established the machines and set on fire the wooden towers of the enemy; by which means he obtained possession of the quay and of the outer harbour along with it. A rampart equalling the city wall in height was here constructed, and the town was now at length completely blockaded by land and sea, for the inner harbour could only be reached through the outer. To ensure the completeness of the blockade, Scipio ordered Gaius Laelius to attack the camp at Nepheris, where Diogenes now held the command; it was captured by a fortunate stratagem, and the whole countless multitude assembled there were put to death or taken prisoners. Winter had now arrived and Scipio suspended his operations, leaving famine and pestilence to complete what he had begun.