The third front was covered by the river Huerba, the deep bed of which was close to the foot of the ramparts. Behind this stream a double entrenchment was carried from the bridge-head to the large projecting convent of Santa Engracia, a distance of two hundred yards. Santa Engracia itself was very strongly fortified and armed; and, from thence to the oil manufactory, the line of defence was prolonged by an ancient Moorish wall, on which several terraced batteries were raised, to sweep all the space between the rampart and the Huerba. These batteries, and the guns in the convent of Santa Engracia, likewise overlooked some works raised to protect a second bridge that crossed the river, about cannot-shot below the first. Upon the right bank of the Huerba, and a little below the second bridge, stood the convent of San Joseph, the walls of which had been strengthened and protected by a deep ditch with a covered way and pallisade. It was well placed to impede the enemy’s approaches, and to facilitate sorties on the right bank of the river; and it was, as I have said, open, in the rear, to the fire of the works at the second bridge, and both were again overlooked by the terraced batteries, and by the guns of Santa Engracia. The fourth front was protected by the Huerba, by the continuation of the old city wall, by new batteries and entrenchments, and by several armed convents and large houses. Beyond the walls the Monte Torrero, which commanded all the plain of Zaragoza, was crowned by a large, ill-constructed fort, raised at the distance of eighteen hundred yards from the convent of San Joseph. This work was covered by the royal canal, the sluices of which were defended by some field-works, open to the fire of the fort itself. [Sidenote: Cavalhero.] On the left bank of the Ebro the suburb, built in a low marshy plain, was protected by a chain of redoubts and fortified houses. Finally, some gun-boats, manned by seamen from the naval arsenal of Carthagena, completed the circuit of defence. The artillery of the place was, however, of too small a calibre. There were only sixty guns carrying more than twelve-pound balls; and there were but eight large mortars. There was, however, no want of small arms, many of which were English that had been supplied by colonel Doyle. These were the regular external defences of Zaragoza, most of which were constructed at the time, according to the skill and means of the engineers; but the experience of the former siege had taught the people not to trust to the ordinary resources of art, and, with equal genius and resolution, they had prepared an internal system of defence infinitely more efficacious.