In the year 415 B.C., the seventeenth year of the Peloponnesian war, the Athenians despatched a great naval and military expedition to the distant island of Sicily. The expedition encountered many difficulties: the Athenians sent strong reinforcements: but in the year 412 B.C. their fleet suffered a crushing defeat in the Great Harbour of Syracuse, and their army was afterwards completely destroyed. Athens itself was without any adequate defence of ships or sailors or soldiers[186]: the Athenians did their best to supply the deficiency, but there was grave reason to fear that their unaided efforts would not avail to save them, and they greatly desired to get support by making some new alliance. It was certain that no new allies could be found among the Greeks[187], and they could look for no help unless it were from the king of Persia[188]. [186] Thucydides VIII. 1. [187] Thucydides VIII. 2. [188] Aristotle, _Constitution of Athens_, 29, and Thucydides VIII. 47. Alcibiades, the ablest but the most unpatriotic and unscrupulous of the Athenians of that time, was in 412 B.C. an exile from his native city under sentence of death[189]. He had in 415 B.C. been appointed one of the three commanders of the great expedition to Sicily: but, when it was on the eve of starting from Attica, he fell under suspicion of having committed a great crime by wilfully offending one of the gods who protected Athens and of designing to overthrow the Athenian constitution[190]. As however there was no proof of his guilt, legal proceedings could not be immediately instituted, and he was allowed to sail as one of the commanders of the fleet: but when he reached Sicily, he found awaiting him the Salaminia, the swift galley which carried despatches, and on board of her some officers sent by the Athenian assembly to summon him home to stand his trial[191]. These officers had been instructed not to arrest him but merely to bid him come to Athens for trial: accordingly he sailed homeward in his own ship, under escort of the Salaminia. On the way the two ships touched at a port in southern Italy, and Alcibiades went ashore and escaped from his custodians: soon afterwards, getting a passage to the Peloponnesus[192], he went to Sparta and advised the Spartans how they might best defeat the Athenian forces in Sicily[193]. The charges against him were produced before one of the popular law courts at Athens: and, as he did not appear, he was found guilty and condemned to death[194]. [189] Thucydides VI. 61. [190] Thucydides VI. 26-28. [191] Thucydides VI. 53. [192] Thucydides VI. 61. [193] Thucydides VI. 89. [194] Thucydides VI. 61.