In the night of the 27th three breaching-batteries were traced out. The first, between the Picurina and the inundation, to breach the right face of the Trinidad. The second, on the Picurina, to breach the Santa Maria. The third, on a prolonged line of the front attacked, contained three Shrapnel howitzers to scour the ditch and prevent the garrison working in it; for Phillipon, having now discovered the true line of attack, was raising the counterguard of the Trinidad and the imperfect ravelin. At daybreak these works being well furnished with gabions and sandbags were lined with musketeers, who severely galled the workmen employed on the breaching-batteries, and the artillery practice was brisk on both sides. Two of the besiegers’ guns were dismounted, the gabions placed in front of the batteries to protect the workmen were knocked over, and the musketry became so destructive the men were withdrawn to throw up earth from the inside. In the night of the 27th the second parallel was extended on the right, to raise batteries against San Roque and the dam which held up the inundation, and to breach the curtain behind: but the ground was hard, the moon shone brightly, the labourers were quite exposed and the work was relinquished. On the 28th the screen of gabions before the batteries was restored, the workmen resumed their labours outside and the parallel was improved. The besieged then withdrew their guns from San Roque, yet their marksmen still shot from thence with great exactness, and the plunging fire from the castle dismounted two howitzers in one of the counter-batteries. During the night the French observed the tracing-string, marking the direction of the sap in front of San Roque, and a daring fellow, creeping out before the workmen arrived, brought it on the line of the castle fire, whereby some loss was sustained. In the night the howitzer battery was re-armed with twenty-four pounders to play on the San Roque, and a new breaching-battery was traced on the site of the Picurina; the second parallel was extended by sap, and a trench was digged for riflemen in front of the batteries. The 29th a slight sally made on the right bank of the river was repulsed by the Portuguese; but the sap at San Roque was ruined by the enemy’s fire, and the besieged continued to raise the counterguard and ravelin of the Trinidad, and to strengthen the front attacked. The besiegers armed two batteries with eighteen-pounders, which opened next day against Santa Maria, yet with little effect, and the explosion of an expense magazine killed many men.