Battle of the fourth Spartan invasion - 507 B.C.
Kleomenes I was not finished with Athens, he considered himself to have been insulted by the Athenians both in word and deed, he was drawing on forces together from all parts of the Peloponnese, without informing any one of his object; which was to revenge himself on the Athenians and reinstall Isagoras. The Corinthians and the other king of Sparta, Demaratus met him expanding the forces against Athens.
Kleomenes I struck a deal with the Boeotians for them to take towns on their borders with Athens, and the Chalcideans  to cause havoc on the coastline of Athens before they were all to meet up with the Peloponnesians, to attack Athens directly .
Kleomenes I and the armies of the Peloponnese crossed the Isthmus and made their way to Eleusis.
In Athens, a great dilemma had to be sorted out. Trouble struck home on three sides, attacks on the coastline, boader raids from the north and now what looked like the entire Peloponnesian army had were headed towards Athens. Giving up any idea of meeting the invading Boeotians or the pirates of Chalcis, they sent out their entire force out to meet the greater danger of the invading Peloponnesians. When the two forces met, the Corinthians at this time thinking what was all this about, withdrew from the main Spartan contingent . Then Demaratus, who was himself king of Sparta and joint-leader of the expedition, had a massive quarrel with Kleomenes I, and he followed the Corinthians example, and left the battle field with his contingent .
When the rest of the allies saw the Corinthians leave with one of the Spartan kings, the rest dispersed. The army never managed to link up with the forces of Euboea and Boeotia as planned. The expedition quickly turned into a farce and Athens would not have to face another Spartan invasion for more than 70 years.
Being humiliated on the battle field, Kleomenes I had no choice but to withdraw. This was a huge disgrace towards the king.
The Athenians, not needing to even risk any of their hoplites in battle against the Peloponnesians, did not return home to Athens, but marched on directy to confront the invading Chalcideans.