The capture of Lechaeum (392 BC) saw the Spartans take advantage of civil strife within Corinth to capture the port of Lechaeum on the Corinthian Gulf (Corinthian War).
Although most of the early campaigns of the Corinthian War took place in Boeotia, during 393 most of the fighting took place around Corinth, where the allied army was unable to prevent Spartan raids. A peace party soon developed within the city, with the aim of taking Corinth out of the war and possibly joining the Spartan side. The plot was discovered and the pro-war party carried out a massacre of many leaders of the peace party on the last day of the festival of the Eukleia. A number of the younger members of the group escaped from the massacre, and fled to the Acrocorinth. After a few days bad omens convinced them to abandon this position. Some went into exile, while others accepted a promise of safe conduct and stayed within Corinth. However they soon found the situation unacceptable - the new leaders of Corinth had accepted a union with Argos, and two leaders of the internal exiles, Pasimelus and Alcimenes, decided to get in touch with the Spartan commander at Sicyon, Praxitas, and offered to let his troops into the Long Walls.
Just like Athens, Corinth was an inland city with a port linked to the city by long walls. In this case the long walls went north to the Corinthian Gulf and connected the city to the port of Lechaeum.
Praxitas didn't have many troops at his disposal, but he knew and trusted Pasimelus and Alcimenes, and decided to take advantage of their offer. He had one 'mora' of Spartans (around 600 men), a force from Sicyon (possibly 1,500 strong) and 150 Corinthian exiles, as well as a small force of cavalry.
On the agreed day Pasimelus and Alcimenes arranged to be on guard at one of the gates into the Long Walls. Praxitas sent one man in first to make sure the situation was safe, and then led his men into the space between the walls. The two walls were around 1,300m apart, and Praxitas was now worried by his lack of numbers, potentially trapped between the garrisons of Lechaeum and Corinth. He decided to dig in and built a stockade and trench across the gap between the walls.
The allies were caught out and were unable to respond until the following day, by which time a force of Argives had arrived to reinforce the defenders of Corinth. The allied force advanced towards the Spartans, triggering an unusual battle fought between the two long walls.
The Spartans were drawn up with the Spartan troops on the right, the exiles on the left and the contingent from Sicyon in the centre.
On the allied side the Corinthians were on the left, facing the Spartans. A mercenary force under the Athenian leader Iphicrates was on the right and the Argives were in the centre.
Once the battle began the Argives defeated the Sicyonians and pursued them north towards Lechaeum. The Spartan cavalry continent dismounted and attempted to hold their ground, but they were wiped out, along with their commander Pasimachus.
Elsewhere the Corinthian exiles defeated Iphicrates's men, and advanced all the way to the city walls of Corinth. On the other flank the Spartans advanced past their palisade and then turned left and advanced into the middle of the battlefield, keeping the palisade to their left. This meant that the Argives were trapped, and they attempted to race to safety. The Argives moved up the centre and eastern part of the gap between the walls. Those in the centre ran into the Spartans and suffered heavy losses, but those in the east were able to reach the city walls. Once there they ran in the exiles and were forced to swerve right. They were then attacked from the back by the Spartans, and trapped against the city walls suffered very heavy losses. The Spartans then turned back north and captured Lechaeum, killing most of the garrison.
The Corinthians and Argives acknowledged their defeat and asked for a truce to recover their dead. The Spartans moved up reinforcements. Praxitas demolished large parts of the long walls, leaving big enough gaps for an army to march through. He then advanced east across the Isthmus of Corinth and captured the ports of Sidus and Crommyon on the Saronic Gulf, built a fort to defend Sparta's allies, before withdrawing and disbanding his main army.
The allies recaptured Lechaeum in the following year, but lost it again in 391 BC. It then remained in Spartan hands for the rest of the war. However in 390 BC it was the site of a humiliating defeat for a force of Spartan hoplites, who were ambushed and defeated by Iphicrates and his light troops (battle of Lechaeum or Corinth, 390 BC).