The battle of Lechaeum or Corinth (390 BC) was a rare defeat for Spartan hoplites at the hands of light troops, commanded by the Athenian Iphicrates (Corinthian War).
In 390 Agesilaus II of Sparta led an invasion of Corinthian territory, operating in the area to the north-east of the city. This coincided with the biannual Hyacinthia festival at Amycles, and so Agesilaus left all of his Amyclaean troops at Lechaeum, the port of Corinth captured earlier in the war), so they could begin the journey home.
The general in command of the Spartan garrison at Lechaeum decided to escort the Amyclaeans west towards friendly territory at Sicyon. He left his allied troops to guard the port, and used his 600 Spartan hoplites and a force of cavalry as the escort. He accompanied the Amyclaeans to within three miles of Sicyon and then decided to divide his forces. The cavalry was ordered to escort the Amyclaeans as far as they required, while the 600 infantry turned back and marched towards Lechaeum.
This attracted the attention of the Athenian commanders in Corinth, Callias son of Hipponicus (and grandson of the diplomant famous for the peace of Callias), commanded the Athenian hoplites and Iphicrates commanded a force of light peltasts. They decided that the peltasts would be able to defeat the slower moving hoplites, attacking them from their vulnerable (unshielded) right side as they marched along the coastal road.
The Athenians deployed their hoplites outside Corinth to act as a reserve and sent the peltasts to attack the Spartans. They advanced to within javelin range, and started to wound a handful of Spartans. The wounded were sent ahead into Lechaeum.
The Spartan commander decided to deal with the threat by sending some of his younger men to attack the peltasts, a tactic known as 'running out'. The first Spartan attack used the ten-years service men (aged between 18 and 28). The peltasts retreated as the hoplites approached, and then attacked when the hoplites began to withdraw, with their formation broken by the charge. Nine or ten Spartans were killed in this first attack. The peltasts continued to harass the Spartan lines, and once again the commander ordered an attack, this time with the fifteen years service men (aged 28-33). Once again this ended in failure, this time with heavier losses.
At this point the Spartan cavalry returned, but the Spartans failed to take advantage of them. Instead of using the cavalry to charge the peltasts, an attack that would probably have succeeded, the horsemen were used to accompany the hoplites. This attack also ended in failure and the Spartans were forced onto a small hill where they prepared for a last stand. At this point the Athenian hoplites advanced, and the Spartan survivors broke and fled. Some ran to nearby sea, while a few made it safely back into Lechaeum. The ones who went to the sea appear to have been rescued by boat. Even so the Spartans lost 250 dead in this fight, or nearly half of the mora.
This defeat forced Agesilaus to temporarily abandon his campaign and return to Corinth to recover the bodies. This turned out to be unnecessary and he returned to the attack. However the news of the defeat altered the attitude of a Boeotian delegation that had been discussing peace terms, and the war continued. Agesilaus soon ended his campaign to the north-east of Corinth and returned home. Iphicrates went on to recapture a number of positions previously taken by the Spartans, including Sidus, Crommyon and Oenoe.
Although the defeat shocked the Spartans, it had little impact on the war. The Spartans continued to hold on to Lechaeum, but were still unable to threaten Corinth itself. It did mark the end of significant campaigning on the Corinth front, but the fighting continued elsewhere.