The besieged had no notion whatever as to the front which would, on this third attempt, be selected for the attack of the British. The elaborate fortifications and improvements made in the Castle and San Cristobal tend to show that these old points of attack were expected to be once more assailed. Hence the besiegers got the inestimable advantage of an unmolested start on the night of March 17th. Colonel Fletcher had risked the dangers of drawing the first parallel at a very short distance from the Picurina fort. On a night of tempestuous rain and high wind, a parallel 600 yards long was picketed out, on a line ranging only from 160 to 200 yards from the covered-way of the work, and 1,800 workmen in the course of the night threw up the parallel, and 4,000 feet of a communication-trench, leading backward to the head of a ravine in the hill of San Miguel, which gave good cover for bringing men and material up from the rear. Not a shot was fired by the French all through the night, and at dawn the parallel and approach were already 3 feet deep and 3 feet 6 inches wide--a good start. With daylight the enemy discovered what had been done, and opened a furious fire both of cannon and musketry upon the trenches. The three nearest bastions of the fortress joined in with their heavy guns, but the 18th was a day of such constant rain that even at a distance of only 500 or 600 yards it was impossible to see much, or take accurate aim at the trenches. The working parties went on deepening and improving the parallel and the communication behind it, without suffering any great loss. During the night of the 18th-19th they were able to trace out and begin two batteries, destined to breach the Picurina, in the line of the parallel, and to extend it at both ends, from the Rivillas on one side to the foot of the hill of San Miguel on the other.