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].’ [186] See Barrié’s report in appendix to Belmas, iv. p. 299.