From 378 BC to 356 BC, Timotheus frequently held command as "strategos" in the wars between Athens (in alliance with Thebes), and Sparta. At this time, Athens' ambition was to revive the Delian League and to regain command of the sea. In 375 BC, during the Boeotian War, Timotheus was sent with a fleet to sail round Peloponnesus by way of a demonstration of Athens' power against Sparta. He persuaded Cephallenia to side with Athens and secured the friendship of the Acarnanians and Molossians. In 373 BC Timotheus was appointed to the command of a fleet for the relief of Corcyra, then beleaguered by the Spartans. But his ships were not fully manned, and to increase their manpower he cruised in the Aegean. The delay upset the Athenians, who brought him to trial; but, thanks to the intervention of his allies - Jason, tyrant of Pherae, and Alcetas I of Epirus, King of the Molossians, both of whom went to Athens to plead his cause - he was acquitted. In way of support, Amyntas, King of Macedon, sent timber to Timeotheus' house in the Piraeus. Upon his acquittal, he went to sea with his fleet and captured Corcyra and then defeated the Spartans at sea off Alyzia (Acarnania). However, with little money to his name—for he had used his own funds to build up the Athenian fleet—he left Athens and took service with the king of Persia as a mercenary.