A sap was to be pushed from the parallel as near the first wall as possible, without being seen into from the upper works, and from thence the engineer was to proceed by gallery and mine. When the first mine should be completed, the battery on the hill of San Michael was to open against the second line of defence, and the assault was to be given on the first line. If a lodgement was formed, the approaches were to be continued against the second line, and the battery on San Michael was to be turned against the third line, in front of the White Church, because the defences there were exceedingly weak. Meanwhile a trench for musketry was to be dug along the brow of San Michael, and a concealed battery was to be prepared within the horn-work itself, with a view to the final attack of the Napoleon battery. The head-quarters were fixed at Villa Toro, colonel Burgoyne conducted the operations of the engineers, colonel Robe and colonel Dickson those of the artillery, which consisted of three eighteen-pounders, and the five iron twenty-four-pound howitzers used at the siege of the Salamanca forts; and it was with regard to these slender means, rather than the defects of the fortress, that the line of attack was chosen. When the horn-work fell a lodgement had been immediately commenced in the interior, and it was continued vigorously, although under a destructive fire from the Napoleon battery, because the besiegers feared the enemy would at day-light endeavour to retake the work by the gorge; good cover was, however, obtained in the night, and the first battery was also begun. The 21st the garrison mounted several fresh field-guns, and at night kept up a heavy fire of grape, and shells, on the workmen who were digging the musketry trench in front of the first battery. The 22d the fire of the besieged was redoubled, but the besiegers worked with little loss, and their musketeers galled the enemy. In the night the first battery was armed with two eighteen-pounders and three howitzers, and the secret battery within the horn-work was commenced; but lord Wellington, deviating from his first plan, now resolved to try an escalade against the first line of defence. He selected a point half-way between the suburb of San Pedro and the horn-work, and at midnight four hundred men provided with ladders were secretly posted, in a hollow road, fifty yards from the wall, which was from twenty-three to twenty-five feet high but had no flanks; this was the main column, and a Portuguese battalion was also assembled in the town of Burgos to make a combined flank attack on that side. SECOND ASSAULT. [Sidenote: Lord Wellesley’s speech, House of Lords, 12th March 1813.]