The battle of Sybota (433 BC) was an inconclusive naval battle between Corinth and Corcyraean that saved Corcyra from invasion, but that also played a part in the outbreak of the Great Peloponnesian War.
The Corinth-Corcyra War (435-431 BC) broke out because of a dispute over the city of Epidamnus, on the Illyrian coast (modern Albania). The city was a colony of Corcyra (Corfu), but its official founder had been provided by Corinth, Corcyra's mother city. Since then relationships between Corinth and Corcyra had broken down. Just before the outbreak of the war the Democratic faction in Epidamnus had expelled the Aristocrats. The exiles allied with the local Illyrians, and began to raid Epidamnus. Both sides asked for help from Corcyra. The Democrats returned empty handed, and then turned to Corinth for help. Corinth provided new settlers and military support. Corcyra responded by besieging Epidamnus (435 BC). Corinth sent a relief fleet, but this was defeated in the naval battle of Leucimme (435 BC). On the same day Epidamnus surrendered.
Corcyra held the advantage for the next year, but in the summer of 434 a Corinthian fleet and army took up a position just to the south of Corfu. A stalemate followed and lasted until the winter of 434-433, when both fleets returned home. Corinth began to build a more powerful fleet and gather allies. This worried the previously neutral Corcyraeans, who decided to try and join the Athenian League. After listening to Corcyraean and Corinthian envoys the Athenians decided in favour of the Corcyraeans and agreed to a defensive alliance. A small squadron of ten ships was sent to Corcyra, with orders to avoid combat with the Corinthians unless they were trying to invade Corcyraean territory.
The Corinthian fleet eventually contained 150 ships. Of these 90 came from Corinth, twenty-seven from Abracia, twelve from Megara, ten each from Leucas and Elis and one from Anactorium. The Corcyraean fleet was smaller, with 120 of their own ships and the ten ships from Athens, but at first the Athenians attempted to stay out of the direct fighting. With 280 ships engaged, the resulting battle was the largest yet to take place between two Greek fleets.
The Corcyraean camp was on Cape Leucimme, at the southern tip of Corfu. Their fleet anchored in the Sybota islands, a small cluster of islands close to the mainland directly opposite the southern tip of Corfu. The Corinthian fleet was in a harbour close to the headland of Chimerium, a short distance to the south of the Sybota islands, close to the point where the River Acheron flows into the sea. At this point the channel between Corfu and the mainland is about five miles wide, so the tactics of the battle that followed weren't forced on the combatants by a lack of space.
The Corinthian fleet put to sea on the night before the battle, and presumably sailed north towards the channel between Corfu and the mainland. The Corcyraean fleet was already at sea, and the two fleets soon came into sight of each other. The main part of the Corcyraean fleet was made up of their own ships, arranged into three squadrons. The ten Athenian ships took up a position at the right of the line. The Corinthian fleet was arranged with the ships from Megara and Ambracia on the right, the ships from Corinth on the left, facing the Athenians and the Corcyraean right, while the remaining Corinthian allies made up the centre of the line. Both fleets carried large numbers of hoplites, archers and javelin throwers, and the resulting battle was more of a boarding action than a typical Athenian naval battle. Thucydides described it as being 'more like a battle on land than a naval engagement', and as lacking skill on both sides.
In the first part of the battle the Athenians attempted to remain out of the fighting, only approaching the fray when a Corcyraean ship appeared to be in difficult. At the other end of the line, the Corcyraean left defeated the Corinthian right, but instead of turning in to attack the centre of the Corinthian line twenty of the ships on the Corcyraean left pursued their defeated enemies back to land and sacked their camp. On the Corcyraean right/ Corinthian left it was the Corinthians who were victorious. As the battle developed the Athenians became increasingly involved in the fighting, until they were openly engaged with Corinthian ships, but even this could not save the situation.
Eventually the Corcyraeans and Athenians were forced back to land. At this point the Corinthians stopped to collect their dead and take them back to Sybota. This was one of the acknowledged signs of victory in Ancient Greek warfare, and the Corinthians were able to retrieve most of their own dead. After this they put back out to sea and approached the Corcyraean fleet. Fearing that the Corinthians were planning to land on Corfu, the surviving Corcyraean and Athenian ships also came out to meet them, and it seemed that the battle would soon be resumed. Just before the two fleets reached combat range the Corinthians spotted twenty fresh Athenian ships approaching from the south. Fearing that they were the advance guard of a larger fleet, the Corinthians reversed direction and retired to Sybota, occupying the harbour that had been used by the Corcyraeans before the battle.
On the following day the surviving Corcyraean ships and all thirty of the Athenian ships approached Sybota and offered battle, but the Corinthians were unwilling to risk a further engagement. Instead they sent an envoy to the Athenian ships to find out if a state of war existed between them. The Athenians replied that they would stop the Corinthians attacking Corcyra, but wouldn't stop them sailing away in any other direction. This assurance was enough for the Corinthians, and they sailed for home, taking 1,050 Corcyraean prisoners with them. Of these prisoners 800 were already slaves, and they were sold, while the remaining 250 free Corcyraeans were kept prisoner, in the hope that they might be used as a fifth column later in the war.
In the aftermath of the battle both sides claimed victory and erected trophies. The Corinthian trophy was on the mainland opposite the Sybota islands. They had the best claim to a victory on the day of battle itself, having take over 1,000 prisoners, destroyed 70 ships and remained in possession of the general area of the battle at the end of the day. The Corcyraean trophy was on Sybota Island. They had destroyed 30 ships, and had only been able to collect some of their dead because the tides had swept the bodies towards them. Their main claim to victory was that the Corinthians had abandoned the campaign and returned home. Both claims now have their supporters - in my opinion the Corinthians won the battle on the first day, but threw away their victory on the following day by refusing the fight when they still had 120 ships from their original 150, while the Corcyraean and Athenian fleet had been reduced to 80 from the original 130 plus 20 reinforcements.
In the aftermath of the battle of Sybota the Corinth-Corcyra War lost its intensity, and was soon subsumed within the wider Great Peloponnesian War. The Corcyraeans served as allies of Athens, while Corinth fought alongside Sparta