By the 4th of September, the town, which caught fire soon after the assault, from the quantity of ammunition and combustibles of all sorts scattered about, was nearly consumed, and the fire became a great impediment to carrying the approaches forward.
Up to the 7th, the enemy had fired but very little since the assault; and by this evening, the roofs of the unburnt houses and steeples had been prepared for musketry, to open at the time of the assault on the castle.
On the 8th, at ten A.M., all the batteries opened on the castle; viz.,—from the left of the attack:—No. 7, with three twenty-four pounders, against the Mirador; No. 8, with three eighteen-pounders, against the lower defences; No. 9, with seventeen twenty-four pounders, against the Mirador and battery de la Reyna; island, with two twenty-four pounders and one eight-inch howitzer, to sweep the back of the castle. From the right of the attack, thirty-three pieces of ordnance against the castle generally. The fire was extremely powerful and well-directed, ploughing up every part of the confined space of the castle. The enemy kept concealed chiefly in little narrow trenches, which they had made along the front of the heights, but they evidently lost many men. About twelve, a white flag was hoisted, and the garrison surrendered prisoners of war. Their numbers had been reduced to 80 officers and 1,756 men, of whom, 23 officers and 512 men were in the hospital.
The loss of the besiegers during the attack was,—53 officers and 898 men killed; 150 officers and 2,340 men wounded; 7 officers and 332 men missing.
There were used at this siege 2,726 gabions, 1,476 eighteen-feet fascines, and 20,000 sand-bags.
The expenditure of ammunition during the siege was,—
| Round shot | { | 24-pounders | 43,367 | } | 52,670 |
| { | 18-pounders | 9,303 | } | ||
| Grape shot | 24-pounders | 2,094 | 2,094 | ||
| Spherical shells | { | 24-pounders | 1,930 | } | 4,278 |
| { | 18-pounders | 150 | } | ||
| { | 8-inch | 2,198 | } | ||
| Common shells | { | 10-inch | 3,755 | } | 11,521 |
| { | 8-inch | 7,766 | } | ||
| Total shot and shells | 70,563 | ||||
| Powder, whole barrels, 90 lbs. each | 5,579[21] | ||||