Accordingly, they took their start from the postern-gate near the grove of Apollo Temenitês; a gate in the new wall, erected four or five months before, to enlarge the fortified space of the city. From this point, which was lower down on the slope of Epipolæ than the Athenian circle, they carried their palisade and counter-wall up the slope, in a direction calculated to intersect the intended line of hostile circumvallation southward of the Circle. The nautical population from Ortygia could be employed in this enterprise, since the city was still completely undisturbed by sea, and mistress of the great harbor, the Athenian fleet not having yet moved from Thapsus. Besides this active crowd of workmen, the sacred olive-trees in the Temenite grove were cut down to serve as materials; and by such efforts the work was presently finished to a sufficient distance for traversing and intercepting the blockading wall intended to come southward from the Circle. It seems to have terminated at the brink of the precipitous southern cliff of Epipolæ, which prevented the Athenians from turning it and attacking it in flank; while it was defended in front by a stockade and topped with wooden towers for discharge of missiles. One tribe of hoplites was left to defend it, while the crowd of Syracusans who had either been employed on the work or on guard, returned back to the city. During all this process, Nikias had not thought it prudent to interrupt them.[375] Employed as he seems to have been on the Circle, and on the wall branching out from his Circle northward, he was unwilling to march across the slope of Epipolæ to attack them with half his forces, leaving his own rear exposed to attack from the numerous Syracusans in the city, and his own Circle only partially guarded. Moreover, by such delay, he was enabled to prosecute his own part of the circumvallation without hindrance, and to watch for an opportunity of assaulting the new counter-wall with advantage. Such an opportunity soon occurred, just at the time when he had accomplished the farther important object of destroying the aqueducts, which supplied the city, partially at least, with water for drinking. The Syracusans appear to have been filled with confidence, both by the completion of their counter-wall, which seemed an effective bar to the besiegers, and by his inaction. The tribe left on guard presently began to relax in their vigilance: instead of occupying the wall, tents were erected behind it to shelter them from the midday sun; while some even permitted themselves to take repose during that hour within the city walls. Such negligence did not escape the Athenian generals, who silently prepared an assault for midday. Three hundred chosen hoplites, with some light troops clothed in panoplies for the occasion, were instructed to sally out suddenly and run across straight to attack the stockade and counter-wall; while the main Athenian force