The battle of Miletus (412 BC) was an Athenian victory fought outside the walls of Miletus, but that was followed almost immediately by the arrival of a Peloponnesian fleet and an Athenian retreat (Great Peloponnesian War).
After the Athenian defeat at Syracuse the Spartans decided to try and encourage a series of revolts in the Athenian Empire. Miletus, encouraged by the Athenian exile Alcibiades, was one of the cities to revolt, and soon became the main Spartan base in the area. A small force of five ships under Chalcideus was sent to the city, while the Athenians responded by blockading the city with twenty ships. This force won a minor victory at Panormus, in which Chalcideus was killed, but the real attack on the city had to wait until Athenian reinforcements had arrived.
The reinforcements arrived towards the end of the summer. They consisted of 1,000 Athenian hoplites, 1,500 Argives, of whom 1,000 were hoplites and 500 light troops who had been given heavy army in Athens, and 1,000 hoplites from the Athenian Empire. They were carried on a fleet of 48 ships, and were commanded by three generals - Phrynichus, Onomacles and Scironides. This fleet crossed the Ageanan to Samos, and then sailed directly to Miletus, landing close to the city.
The army that came out to oppose them was a good cross-section of the alliance that would eventually defeat Athens. Miletus, a former member of the Empire, provided 800 hoplites. The Spartans provided the force of Peloponnesians that had accompanied Chalcideus. The Persians provided two forces - a group of hired mercenaries, and their own cavalry, commanded in person by the local satrap Tissaphernes. Sadly Thucydides gives no numbers for these forces.
The battle began with a general advance along the Athenian line, but the Argives got ahead of the rest of the army, believing that as Dorian Greeks they would have no problem defeating the Ionian Milesians. During their advance the Argives became somewhat disorganised, and they suffered a costly defeat, losing 300 of their 1,500 men.
On the other flank the Athenians were victorious, defeated the Peloponnesian contingent first, then turning on the Persian contingent. Seeing the defeat of the rest of their army the Milesians retreated back into their city. Alcibiades, who had been fighting with the Tissaphernes, escaped from the battlefield and made his way to Teichiussa on the coast, where he was lucky enough to find a Peloponnesian fleet of 55 ships that had just arrived.
Meanwhile the Athenians at Miletus built a trophy to commemorate their victory, and then prepared to build a blockading wall across the isthmus that connected the city to the mainland. At this point news of the new Peloponnesian fleet reached them. Most of the army wanted to stand and fight, but Phrynichus refused to take part in a battle against a larger enemy force with Athens's last major fleet. He got his way, and that evening the entire Athenian force retreated to Samos. The Argive contingent, angry after their own defeat and now seeing the results of the battle thrown away, left the allied army and sailed for home.