Aigospotamoi: the final battle of the Peloponnesian War (431-404). In September 405, the Athenians were decisively defeated by the Spartans and lost their navy. As a result, the siege and fall of Athens became inevitable.
The road to Aigospotamoi: Confrontation course
After the Amorges affair, the Spartans were financed by Persian gold and did have the means to force a decisive victory. Having built a mighty fleet, they tried to force the allies of Athens to desert their master. If they were successful, the Spartans demanded new ships from their newly won allies, which even further increased the strength of their fleet. In this manner Sparta managed to gain a fleet capable of confronting the mighty Athenian flotilla.
Sparta received support from Cyrus the Younger, the Persian satrap responsible for the Aegean frontier. Cyrus' authority reached further than Ionia alone: it included Lydia, Phrygia and Cappadocia as well. He primarily assisted the Spartans by providing their admiral Lysander with funds to build and maintain a fleet and to pay its rowers their due.
The relationship between Cyrus and Lysander was partly based on the Persian strategy of damaging Athens, which had in the past often raided the Achaemenid ports. A chance to strike a blow at Athens without having to send an expensive expedition was something king Darius II Nothus was not likely to ignore.
Besides, the relationship between the Persian satrap and the Spartan admiral was the result of overlapping interests. Cyrus aspired to the Persian throne and needed powerful allies - like Lysander, who enjoyed a position of prominence throughout Greece and was skilled in the art of war. That Cyrus regarded Lysander as a suitable friend can be deduced from the fact that, in his absence, he named Lysander as his stand-in with all royal privileges to match, like the collecting of taxes.note[Donald Kagan, The Fall of the Athenian Empire (1987) 381.] Lysander benefited from this alliance in another way: Cyrus' money allowed him to continue the war against Athens.
Before the battle of Aigospotamoi, several naval battles had been fought. However, neither the Spartan defeats near Cynossema, Abydus (both in 411), and Cyzicus (410), nor the Athenian defeat at Notium (406) had proved decisive. The battle of Arginusae (406), however, had been an important Athenian victory. On that occasion, Sparta had been forced to join battle under unfavorable circumstances, which had cost her 77 ships, or 64% of her fleet. The ongoing defeats had reduced the Spartans' will to continue the war, despite the constant flow of Persian gold, which would unquestionably allow them to raise a new fleet. The defeat at Arginusae convinced Sparta to offer Athens peace.
From the Spartan point of view this offer is understandable. The remnants of the Spartan fleet, now stationed at Chios, had run out of supplies and out of money, and chances for victory were slim. Only once had Sparta been able to defeat the Athenians at sea: at Notium. And even that victory had to be attributed rather to an Athenian misjudgment than to a well-executed Spartan plan. To boot, in the recent confrontation at Argisunae, the Athenians (with a relatively inexperienced fleet, into which even non-Athenians and slaves were recruited) had managed to beat one of Sparta's most powerful and battle-hardened navies. Last of all, there was a substantial faction in Sparta that desired peace because it feared Lysander's increasing power. He owed much of his reputation to his close relationship with Cyrus made some even suggest Lysander was collaborating with Cyrus. It was feared that Cyrus would start asking favors in exchange for the continued funding. If Sparta was not to become a client state of Persia, it should take care not to become too dependent on its privileged relationship with Cyrus and certainly not too dependent on Persian gold.note[Idem, 321.]
So, in the winter of 406/405, the following offer was made to Athens: the upholding of the status quo and, as a token of her good will, the evacuation of Decelea. Quite an acceptable offer -from an Athenian point of view- as the Athenians would not have to dismantle their alliance. Moreover, the state funds had almost dried up, making it difficult to maintain large forces. Athens needed time to restore order in the Delian League and reinvigorate its commercial activities.
Still, the Athenians declined the Spartan peace offer. It is tempting to accept the explanation offered by Aristotle (Athenian Constitution, 34.1), and blame the ignorant mass, deceived by demagogues, for refusing peace. The American scholar Kagan, however, argues that the Athenian people must have seen through the offer. He provides us with several reasons why Athens ought to have turned down the peace offer. First of all, the Athenians could not sufficiently trust Sparta, which had violated the Peace of Nicias.note[After concluding this peace treaty, Sparta had refused to hand over Amphipolis, and had the Boeotians to demolish the Athenian fort of Panactum. And in 413, Sparta had occupied Decelea - an act of unprovoked aggression.] Secondly, the Athenians believed that the Spartan offer was a deception, intended to gain time to construct a new navy.
So, the Athenians refused to swallow the bait. They would strike at the remnants of the Spartan fleet. If they could destroy the Spartan fleet before Persian gold arrived, there might be a chance that the Persian king would grow weary of seeing his investment come to nothing. It was a perilous course: the Athenians based their policy on the assumption that king Darius would stop subsidizing the Spartan war effort if the Spartans were unable to deliver the goods. History had taught, however, that Persian kings tended to become discouraged by defeats and waste of gold. Besides, the Athenians hoped that the Spartan peace offer, a clear violation of Sparta's treaty with Darius, would stir up bad blood in Persia.
After the decision had been taken to continue the war, the Athenians started to address the problem of how best to defeat the remainder of the Spartan fleet. The first plan was to lure the Spartans out to sea. The Spartans were not tempted though. They would remain at Chios until reinforced or until relieved. With no chance of a decisive confrontation the Athenian fleet finally put to sea. For the rest of the season of 406 they would plunder the coastal towns of Sparta and her allies.
The results of the battle of Arginusae were jubilantly celebrated in Athens, but at the same time the admirals were accused of not having been able to force a decisive victory. This accusation, in combination with the scandal that had arisen due to the admirals' failure to salvage the bodies of the dead and rescue the survivors, resulted in the admirals being brought to court. At the trial, six out of eight admirals were convicted to either banishment or death. Never before had an Athenian admiral been sentenced to death. The competence and experience of all six admirals would be missed during the next year.