We must take particular note of these propositions in order to understand the conduct of Nikias during the present critical interval. He had been from the beginning in secret correspondence with a party in Syracuse;[384] who, though neither numerous nor powerful in themselves, were now doubtless both more active and more influential than ever they had been before. From them he received constant and not unreasonable assurances that the city was on the point of surrendering, and could not possibly hold out. And as the tone of opinion without, as well as within, conspired to raise such an impression in his mind, so he suffered himself to be betrayed into a fatal languor and security as to the farther prosecution of the besieging operations. The injurious consequences of the death of Lamachus now became evident. From the time of the departure from Katana down to the battle in which that gallant officer perished,—a period seemingly of about three months, from about March to June 414 B.C.,—the operations of the siege had been conducted with great vigor as well as unremitting perseverance, and the building-work, especially, had been so rapidly executed as to fill the Syracusans with amazement. But so soon as Nikias is left sole commander, this vigorous march disappears and is exchanged for slackness and apathy. The wall across the low ground near the harbor might have been expected to proceed more rapidly, because the Athenian position generally was much stronger, the chance of opposition from the Syracusans was much lessened, and the fleet had been brought into the Great Harbor to coöperate. Yet in fact it seems to have proceeded more slowly; Nikias builds it at first as a double wall, though it would have been practicable to complete the whole line of blockade with a single wall before the arrival of Gylippus, and afterwards, if necessary, to have doubled it either wholly or partially, instead of employing so much time in completing this one portion that Gylippus arrived before it was finished, scarcely less than two months after the death of Lamachus. Both the besiegers and their commander now seem to consider success as certain, without any chance of effective interruption from within, still less from without; so that they may take their time over the work, without caring whether the ultimate consummation comes a month sooner or later. [384] Thucyd. vii, 49-86.