The battle of Coronea (394 BC) was an inconclusive Spartan victory that saw Agesilaus II defeat an allied army that was attempting to block his path across Boeotia, but not by a big enough margin to allow him to continue with his invasion (Corinthian War, 395-386 BC).
At the start of the war the Spartans had suffered a setback that cost them two of their leaders. The great war leader Lysander, largely responsible for their victory in the Peloponnesian War, was killed at the battle of Haliartus in Boeotia. King Pausanias, who arrived a day or two later, was put on trial for arriving later and failing to fight to retrieve Lysander's body, and fled into exile. The second Spartan king, Agesilaus, was absent in Asia Minor fighting the Persians (Persian-Spartan War. 400-387 BC), but in the aftermath of Haliartus he was recalled to Greece.
Agesilaus decided to take the land route home and bring a sizable army with him. He had no trouble convincing the Greeks of Asia Minor to accompany him, but his Peloponnesian contingents were less keen on the idea of abandoning a war against the Persians to fight fellow Greeks and had to be tempted west with promises of prizes for the best contingent. Agesilaus left Asia Minor in the early summer of 394 at the head of around 15,000 men.
His route took him west through Thrace, where he had to fight off attacks and win over a number of cities. At Amphipolis he learnt of the Spartan victory at Nemea, west of Corinth, and ordered the news to be spread. He bluffed his way through Macedon, then in the middle of a period of chaos that followed the murder of King Archelaus. He faced more attacks as he advanced through Thessaly, but won a cavalry victory that cleared his route. After a rapid march from Asia Minor he reached the borders of Boeotia in August 394 BC.
Agesilaus crossed into Boeotia from the north-west just before a partial eclipse of the sun, calculated to have taken place on 14 August 394 BC. On that day news reached him of the disastrous Spartan naval defeat at Cnidas. The Spartan fleet had been destroyed and its commander Peisander had been killed. Agesilaus must have been aware that this meant that the Greek cities of Asia Minor would probably fall to the Persians, making the loyalty of that part of his army suspect. In order to maintain the morale of his men, and probably also to ensure their loyalty, he announced that the battle had been a victory, although he did acknowledge the death of Peisander.
Agesilaus had a typically mixed army. He was sent one 'mora' of Spartan troops from the army at Corinth and was given half of the 'mora' based at Orchomenus, a Spartan ally in Boeotia. The army that he had brought from Asia Minor included a contingent of 'neodamodes', or enfranchised helots, and some of the survivors of the '10,000', the Greek supporters of Cyrus the Younger, now commanded by Herippidas. He had also gained troops from some of the cities he passed on his march, and hoplites from Orchomenus and Phocis.
He was faced by an allied army that had moved back into Boeotia from Corinth. According to Xenophon this included contingents from Boeotia, Athens, Argos, Corinth, Aeniania, Euboea, Western Locris and Eastern Locris. The general assumption is that most of the Boeotia contingent came back from Corinth, accompanied by smaller contributions from most of the other powers. Xenophon doesn't give us troop numbers, but he does say that that both sides had similar numbers of hoplites and cavalry, but that Agesilaus had the advantage in light troops.
The two armies clashed just to the east of Coronea, on the shores of Lake Copais. Agesilaus had moved to Orchomenus then moved south along the western shores of the lake, while the allied army moved to intercept him, taking up a position on the northern foothills of Mount Helicon, south of the lake. Both sides seem to have been eager to fight - as Agesilaus crossed the River Cephisus and advanced into the plains east of Coronea, the allies moved north from the mountains to intercept him.
We don't have many detailed descriptions of ancient Greek battles, so its rather frustrating that Xenophon chose to leave us a more detailed account that normal because there had been 'none like it in our time'.
Agesilaus placed his Spartan troops on his right. The Orchomenians were posted on the left and the other allied troops filled the gap. On the allied side the Thebans were on the right, facing the Orchomenians and the Argives were on the left, facing the Spartans.
The two sides approached each other in silence, until they were one 'stade' apart (about 150-200m). At this point the Thebans shouted a battle cry and advanced at double speed. When the two sides were a little closer the troops in the Spartan centre charged, starting with the survivors of the 10,000 and the enfranchised helots and followed by the Greeks of Asia Minor and the Hellespont.
The Spartans were victorious across most of the line. In the centre there was some fighting before the allied troops fled. On the Spartan right the Argives fled without fighting. Only on the left did things go badly, where the Thebans smashed their way through the Orchomenians and reached the Sparta baggage train. It took some time for this news to reach Agesilaus, who was being crowned with a victory wreath when the news arrived.
This triggered the second phase of the battle, this time with the opposing forces facing in the opposite direction to the first. Agesilaus led his main body towards the Thebans, who probably formed up in an unusually deep formation. Xenophon was rather critical of Agesilaus's decision to fight face to face with the Thebans, suggesting that it would have been safer to let them through then attack them from the rear. Agesilaus had at least two possible motives for his decision - at this stage his Spartans hadn't actually fought, and so he may have wanted to make sure they played an active part in the battle. He may also have been attempting to win a crushing victory that would knock the Thebans out of the war.
The result was a period of vicious melee combat, with 'shield wedged in with shield', fought in a strange silence. Eventually some of the Thebans managed to break through the Spartan lines and rejoined the rest of the army on Mount Helicon. Agesilaus himself was wounded in this phase of the battle.
In the aftermath of the battle eighty of the enemy were found taking shelter in a sanctuary of Athena Itonia, north of the battlefield. Agesilaus made sure they were escorted safely back to their own side.
The result of the battle only became clear on the following morning, when the Spartans drew up in battle order while the Thebans asked for a truce to bury their dead, an admission of defeat. However the allied army was still largely intact, and refused to fight a second battle. Agesilaus decided that it wasn't worth attempting to force his way through the foothills of Mount Helicon to reach Thebes, and retreated west into Phocis.
The Spartans suffered a minor setback in the aftermath of the battle. A raiding force commanded by the polemarch Gylis was sent on a raid into Locris, but he was harassed by Lorcrian light troops as he retreated. The polemarch and all eighteen Spartans who were present were killed, and only a few of the troops escaped. This ended the campaign. Agesilaus disbanded his army, sending the various contingents home or back to their previous posts, and sailed south across the Gulf of Corinth to return to Sparta.
The battle of Coronea was the last full scale battle of the war. It was followed by a period of comparatively small scale warfare around Corinth, raids into the territory of Argos, and fighting in other outlying areas, but the war was eventually decided by the Persians, who made peace with the Spartans and helped impose a pro-Spartan peace agreement in 386 BC (the King's Peace or Peace of Antalcides).