Sections 13–22 act as the introduction to this target passage.
(Twice before during war, in 427 and 425/4 BC, the Athenians had been involved in Sicily, on both occasions on a small scale and in answer to requests for help from allies. Now in 415 BC they were faced with another request, this time from Egesta, and their minds were fixed on much larger prizes.)
The decision to invade Sicily
Athenian motives: the Egestaians provide an excuse to invade Sicily (6.6–7)
Such is the list of the peoples, Hellenic and barbarian, inhabiting Sicily, and such the size of the island which the Athenians were now determined to invade. In fact they were ambitious to conquer the whole of it, although they had also the specious aim of helping their kinsmen and other allies on the island. But they were especially encouraged by envoys from Egesta, who had come to Athens and requested their help more urgently than ever.
The Egestaians had gone to war with their neighbours the Selinountines upon questions of marriage and disputed territory, and the Selinountines had won the alliance of the Syracusans, and attacked Egesta hard by land and sea. The Egestaians now reminded the Athenians of the alliance with the Leontinoi in the time of Lakhes (427), during the previous war, and begged them to send a fleet to their aid. Among a number of other considerations, they urged as their main argument that, if the Syracusans were allowed to go unpunished for their depopulation of Leontinoi, to ruin the allies still left to Athens in Sicily and to get the whole power of the island into their hands, there would be a danger of their one day coming with a large force, as Dorians, to the aid of their Dorian kinsmen, and as colonists, to the aid of the Peloponnesians who had sent them out, and joining these in pulling down the Athenian Empire. The Athenians would, therefore, do well to unite with the allies still left to them, and to make a stand against the Syracusans; especially as they, the Egestaians, were prepared to supply enough money for the war.