Peloponnesian War By Surata Garratt 460 BCE Athens broke its long-standing alliance with Sparta 460 BCE Athens and Argos form an alliance 460 BCE Megara enters the Delian League 460 BCE Athens begins building the long walls Period: 460 BCE to 445 BCE First Peloponnesian War 457 BCE Aegia enters the Delian League 457 BCE Battle of Oenoe Sparta wins 457 BCE Athenian victories 454 BCE Delian League treasury moves to Athens 454 BCE Athens and Sparta sign 5 year treaty