The capture of the fort enabled the second parallel to be pushed on, and breaching batteries to be completed. The guns maintained a heavy fire on the bastion of La Trinidad; and the sappers directed their efforts against the lunette of San Rocque. The progress of the siege was slow; and though two breaches were made, the certainty that both were retrenched[10] and secured by interior defences, rendered an assault too hazardous an experiment to be ventured. [10] _Retrench_, in fortification, means the isolating of a breach by forming inner defences. Lord Wellington was critically circumstanced, as Marmont had made some forward movements in front of Beira, and Soult was advancing, determined to relieve the place. His light troops were already at Larena; the covering army under Hill had been obliged to retreat; and after blowing up two arches of the bridge of Merida, had taken post in front of Talavera. In consequence, the fifth division was ordered to advance, leaving the observation of San Christoval to the Portuguese cavalry; the British general having decided on leaving a corps of ten thousand men to protect the trenches, and with the remainder of his force bring Soult to action. At noon, on the 5th April, the breaches were reconnoitred and declared practicable; but the assault was deferred for another day to allow the artillery time to batter down the curtain, connecting the bastion with an unfinished ravelin. The concentrated fire of the British batteries fell upon the old wall with irresistible force; it was breached in a single day, and thus three points for assault were thrown open. The report of the engineers was encouraging; the main breach was sufficiently wide, and the ascent to all three easy enough for troops to mount. Ten o’clock on the night of the 6th was appointed for the assault to be attempted, and the necessary orders were issued accordingly. The castle was to be attacked by the third division, the bastion of La Trinidad by the fourth, that of Santa Maria by the light division, the lunette of San Rocque by a party from the trenches; while the fifth should distract the garrison by a false attack on the Pardelaras, and the works contiguous to San Vicente.