A history of the Peninsular War, Vol. 5, Oct. 1811-Aug. 31, 1812

by Charles Oman

The sortie recaptured the convent of Santa Cruz, swept along the second parallel, where it upset the gabions and shovelled in some of the earth, and then made a dash at the first parallel, where it might have done much mischief in the batteries if General Graham and the engineer officer on duty had not collected a few belated workmen of the 24th and 42nd, who made a stand behind the parapet, and opened a fire which checked the advance till the relieving division came running up from the rear. The French then turned and retired with little loss into the place.

The advanced parallel and Santa Cruz were not reoccupied while daylight lasted, but at about 4.30 in the afternoon the three batteries opened with the 27 guns, which had been placed in them. Two 18-pounders in the left battery were directed against the convent of San Francisco, the rest against the northern part of the city, on the same point where Ney’s breach had been made in 1810. Of the gunners, 430 in number, nearly 300 were Portuguese[184]. The fire opened so late in the day that by the time that it was growing steady and accurate dusk fell, and it was impossible to judge what its future effect would be.

Meanwhile, when the big guns were silent, the work of preparing for the nearer approach was resumed after dark. The most important move on the night of the 14th-15th was the storming of the convent of San Francisco by three companies of the 40th regiment. The garrison made little resistance, and retired, abandoning three guns and two wounded men. Immediately afterwards the posts in the neighbouring suburb were all withdrawn by Barrié, who considered that he could not afford to lose men from his small force in the defence of outlying works, when his full strength was needed for the holding of the town itself. Santa Cruz, on the other side, though recovered in the morning, was abandoned on this same night for identical reasons. The French general was probably wise, but it was a great profit to the besiegers to be relieved from the flanking fire of both these convents, which would have enfiladed the two ends of the second parallel. That work itself was reoccupied under the cover of the night: the gabions upset during the sortie of the morning were replaced, and much digging was done behind them. The zig-zags of the approach from the upper trenches on the Great Teson were deepened and improved. All this was accomplished under a heavy fire from the guns on the northern walls, which were so close to the second parallel that their shells, even in the dark, did considerable damage.

When day dawned on the 15th, the breaching batteries on the Great Teson opened again with excellent effect. Their fire was concentrated on the rebuilt wall of the enceinte, where the French breach of 1810 had been mended. It was necessary to batter both the town wall proper and the fausse-braye below it, so as to make, as it were, an upper and a lower breach, corresponding to each other, in the two stages of the enceinte. It will be remembered that, as was explained in our narrative of the French siege[185], the mediaeval ramparts of the old wall showed well above the eighteenth-century fausse-braye which ran around and below them, while the latter was equally visible above the glacis, which, owing to the downward slope from the Little Teson, gave much less protection than was desirable to the work behind it. The French breach had been carefully built up; but, lime being scarce in the neighbourhood, the mortar used in its repairs had been of inferior quality, little better than clay in many places. The stones, therefore, had never set into a solid mass, even eighteen months after they had been laid, and began to fly freely under the continuous battering.

The breaching being so successful from the first, Wellington resolved to hurry on his operations, though there were still no signs that Marmont or Dorsenne was about to attempt any relief of the garrison. Yet it was certain that they must be on the move, and every day saved would render the prospect of their interference less imminent. Accordingly it was settled that the second parallel should be completed, and that, if possible, more batteries should be placed in it, but that it was to be looked upon rather as the base from which an assault should be delivered than as the ground from which the main part of the breaching work was to be done. That was to be accomplished from the original parallel on the Great Teson, and one more battery was marked out on this hill, close to the Redout Renaud, but a little lower down the slope, and slightly in advance of the three original batteries. From this new structure, whose erection would have been impossible so long as San Francisco was still held by the French, Wellington proposed to batter a second weak point in the enceinte, a mediaeval tower three hundred yards to the right of the original breach. All the attention of the French being concentrated on the work in the second parallel, this new battery (No. 4) was easily completed and armed in three days, and was ready to open on its objective on January 18th.

Meanwhile the completion of the second parallel proved a difficult and rather costly business. By Wellington’s special orders all the energies of the British batteries were devoted to breaching, and no attempt was made to subdue the fire of those parts of the enceinte which bore upon the trenches, but were far from the points selected for assault. Hence the French, undisturbed by any return, were able to shoot fast and furiously at the advanced works, and searched the second parallel from end to end. It was completed on the 18th, and two guns were brought down into a battery built on the highest point of the Little Teson, only 180 yards from the walls. An attempt to sap forward from the western end of the second parallel, so as to get a lodgement a little nearer to the place, was completely foiled by the incessant fire of grape kept up on the sap-head. After many workmen had been killed, the endeavour to push forward at this point was abandoned, such an advance forming no essential part of Wellington’s scheme. The enemy’s fire on the second parallel was made somewhat less effective on the 16th-18th by digging rifle-pits in front of the parallel, from which picked marksmen kept up a carefully aimed fusillade on the embrasures of the guns to left and right of the breach. Many artillerymen were shot through the head while serving their pieces, and the discharges became less incessant and much less accurate. But the fire of the besieged was never subdued, and the riflemen in the pits suffered very heavy casualties.

The 18th may be described as the crucial day of the siege. The new battery (No. 4) on the Greater Teson opened that morning against the tower which had been chosen as its objective. By noon it was in a very ruinous condition, and at dusk all its upper part fell forward ‘like an avalanche,’ as the governor says in his report, and covered all the platform of the fausse-braye below. Barrié remarks that this point was admirably chosen by Wellington’s engineers, ‘it was unique in the enceinte for the facilities which it offered for breaching and the difficulties for defence. This is the spot where the walls are lowest, the parapet thinnest, and the platforms both of the ramparts and the fausse-braye narrowest. Moreover here had been situated the gun which best flanked the original great breach[186].’

The garrison found it impossible either to repair the breaches or to clear away the débris which had fallen from them. All that could be done was to commence retrenchments and inner defences behind them. This was done with some effect at the great breach, where cuts were made in the ramparts on each side of the demolished section, parapets thrown up behind the cuts, and two 24-pounders dragged into position to fire laterally into the lip of the easy slope of débris which trended up to the ruined wall. At the second or smaller breach much less was accomplished—the warning was short, for it had never been guessed that this tower was to be battered, and the space upon which work could be done was very limited. It was hoped that the narrowness of the gap might be its protection—it was but a seam in the wall compared with the gaping void at the first and greater breach.