Meanwhile the envoys, already mentioned, who had gone from Syracuse to the cities after the capture of Plemmyrium, had succeeded in their mission, and were about to bring the army that they had collected, when Nicias got scent of it, and sent to the Centoripae and Alicyaeans and other of the friendly Sicels, who held the passes, not to let the enemy through, but to combine to prevent their passing, there being no other way by which they could even attempt it, as the Agrigentines would not give them a passage through their country. Agreeably to this request the Sicels laid a triple ambuscade for the Siceliots upon their march, and attacking them suddenly, while off their guard, killed about eight hundred of them and all the envoys, the Corinthian only excepted, by whom fifteen hundred who escaped were conducted to Syracuse.