The naval Battle of Eretria, between Sparta

Sparta

Sparta or Lacedaemon, was a prominent city-state in ancient Greece, situated on the banks of the River Eurotas in Laconia, in south-eastern Peloponnese. It emerged as a political entity around the 10th century BC, when the invading Dorians subjugated the local, non-Dorian population. From c...

 and Athens

Athens

Athens , is the capital and largest city of Greece. Athens dominates the Attica region and is one of the world's oldest cities, as its recorded history spans around 3,400 years. Classical Athens was a powerful city-state...

, took place in September 411 BC, off the coast of Euboea

Euboea

Euboea is the second largest Greek island in area and population, after Crete. The narrow Euripus Strait separates it from Boeotia in mainland Greece. In general outline it is a long and narrow, seahorse-shaped island; it is about long, and varies in breadth from to...

.

Background

During the spring of 411 BC, the Eretria

Eretria

Erétria was a polis in Ancient Greece, located on the western coast of the island of Euboea, south of Chalcis, facing the coast of Attica across the narrow Euboean Gulf. Eretria was an important Greek polis in the 6th/5th century BC. However, it lost its importance already in antiquity...

ns drove the Athenians out of Oropos

Oropos

Oropos is a small town and a municipality in East Attica, Greece.-Geography:It is situated on the southern Euboean Gulf, opposite Eretria. Oropos is located N of Avlona and Athens, E of Thebes and SE of Chalcis. Oropos is linked with the road linking Nea Palatia and Sikamino...

 with the help of the Boetians. This city was a strategic point for Athens because it allowed them to control all of Euboea. Moreover all the commercial traffic was made through the city. The Eretrians would hope that Sparta would help them to end the Athenian rule on Euboea.

Battle

By the end of the summer 411 BC, a large Spartan fleet sailed towards Euboea. The Athenians tried to prevent the Euboeans from switching sides by sending a squadron to Eretria. However, the Eretrians supported the Spartans. While the Athenians were in the harbour of Eretria in order to supply themselves, the Eretrians informed the Spartan admiral

Admiral

Admiral is the rank, or part of the name of the ranks, of the highest naval officers. It is usually considered a full admiral and above vice admiral and below admiral of the fleet . It is usually abbreviated to "Adm" or "ADM"...

 Hegesandridas

Hegesandridas

Hegesandridas or Agesandridas , son of a "Hegesander" or "Agesander", perhaps the same who is mentioned as a member of the last Spartan embassy sent to Athens before the Peloponnesian War, was himself a Spartan general in that war. In 411 BC he was placed in command of a fleet of 42 ships destined...

 by a signal fire that it was an appropriate time to attack. The Athenians hurriedly embarked but were defeated during the naval battle which followed. The Athenians who tried to take refuge in Eretria were killed by the town's inhabitants. Only those who decided to go to the Athenian fort in Eretria (which was likely on the Pezonisi Peninsula) survived.

Aftermath

Following the battle, almost all of Euboea switched side. Then there was a huge debate as to whether the Athenians would take them back, ending up in a massacre of Eretria.