Nicias the son of Niceratus became one of the leading political figures in Athens after the death of Pericles (429). He was very wealthy, deriving most of his income from the silver mines of Laurion.
Early in his career as general, he took the island of Minoa (427), from which he invaded Corinthian territory, but although he won the battle, he gave up the credit for it rather than leave two dead soldiers unburied.
When his political rival Cleon cast doubts on his ability during the siege of Pylos where 400 Spartans were stranded on the island of Sphacteria, Nicias surrendered the command to Cleon (425). At first Cleon was reluctant to take up the command but when he did, he boasted that he would either kill the Spartans or bring them back alive within 20 days. Much to everybody's surprise, he did. This did Nicias' reputation no good at all.
Cleon was later killed at the battle of Amphipolis (422). As Brasidas, the main Spartan instigator of the war, was also killed at the same battle, Nicias took the opportunity to bring about a peace between the two sides (421). Under the peace terms, each side was to return all the cities and territory it had captured from the other. These arrangements were wrecked by Alcibiades in Athens and the pro-Boeotian party in Sparta, and the war started up again.
For a while it seemed likely that either Alcibiades or Nicias would be ostracised, and the whole of Athens was divided into two factions. However, but Alcibiades and Nicias united to have Hyperbolus ostracised instead, and he was in fact the last person to suffer this fate (417).
It was Alcibiades who took up the idea of an Athenian expedition against Sicily, which Nicias was against. When the people voted in favour of the expedition, the generals elected were Nicias, Alcibiades, and Lamachus (415). When Alcibiades was recalled to Athens to stand charges over the mutilation of the Hermae, Nicias was left in charge of the expedition, with Lamachus as his subordinate.
Nicias took the town of Catana, and from there managed to establish a camp in Syracusan territory and start building a wall to circumvallate the town. In a skirmish when the Syracusans were trying to prevent the wall from being finished, Lamachus was killed. However, things seemed to be going well for the Athenians with many Sicilian cities coming over to their side, and the Syracusans preparing to negotiate a surrender.
Nicias grew overconfident and failed to prevent Gylippus of Sparta, who was bringing reinforcements for Syracuse, from landing. He defeated the Athenians, scattering them from their building site, and built a cross-wall to prevent their complete circumvallation of the city. Nicias called for reinforcements from Athens, and asked to be relieved of the command because he was suffering from kidney stones.
Nicias wanted to wait for the reinforcements, but his subordinate generals forced him into a naval operation, which the Athenians lost. When the reinforcements arrived under Demosthenes (413), Nicias tried to persuade him to wear the Syracusans down since time was on the side of the Athenians, with more desertions and defections to their side every day. Demosthenes got his way, and was defeated, sending the whole expeditionary force into a panic.
Ancient Sources:
Plutarch's Life of Nicias
Thucydides: The Peloponnesian War Books 3 to 7
Once the decision to abandon the expedition had been made, the panic was increased by an eclipse of the moon, which Nicias interpreted as meaning that they should wait a month before leaving. He was forced to abandon his position by attacks from the Syracusans, who captured most of the Athenian ships, and the Athenian forces attempted to retreat across the island to a spot from which they could find shipping willing to take them home. Demosthenes was captured during the retreat, and Nicias tried to arrange a truce to allow the Athenians to leave.
The Syracusans and their allies refused, and continued to harry the retreating Athenians. Eventually the Spartans agreed to put an end to the slaughter, remembering that the Spartans captured at Sphacteria had been treated well and eventually released thanks to Nicias. The surviving soldiers were enslaved and put to work in quarries under harsh treatment, while Nicias and Demosthenes were executed by the Syracusans, despite Gylippus' endeavours for him to be handed over to be taken back to Sparta.
