Due to both deference to Sparta and to their cash shortage the Thirty had left Athens' border forts ungarrisoned which allowed a group of Athenian exiles to seize the fort of Phyle in 404/403 BCE. The leader of the exiles, initially only some 70 strong, was Thrasybulus who had a reputation as a moderate democrat and so ideal to unite all democratic opponents of the thirty. A force of Athenian cavalry and Spartans was sent against Phyle, but was defeated in two surprise attacks by Thrasybulus. Thrasybulus then marched on Piraeus and defeated the force the thirty sent against him at the Battle of Munychia.
Sparta first responded by sending Lysander with a force of mercenaries who clearly intended simply to place the thirty back in power. Very quickly, however, Sparta sent King Pausanias with a levy of the Peloponesian League. Pausanias defeated the democrats in the Battle of Piraeus However he opened negotiations and accepted the restoration of democracy but insisted on the separation Eleusis as a safe haven for the oligarchs.
Lysander's faction at Sparta was furious and along with King Agis brought Pausanias to trial to the end of 403 BCE. The exact charge is uncertain but the essence was presumably that he had been soft on Athens. Fifteen of the Gerousia, including Agis, voted guilty and 14 against but all 5 Ephors voted non guilty so he was acquitted.