Battle of Tanagra ( 457 BC ) " There was a later battle at Tanagra during the Peloponnesian War ; see Battle of Tanagra ( 426 BC ) . " The Battle of Tanagra took place in 457 BC between Athens and Sparta during the First Peloponnesian War . Background . Although it had won a hegemony over the Greek city - states from its leadership in the Persian Wars , the Spartan - led Peloponnesian League feared the growing power of the Athenian empire and worsened relations by repeated diplomatic affronts and demands . Wanting to deny any future Persian invasion a base from which to operate , Sparta had urged Athens , along with other Greek cities , to refrain from rebuilding their walls . However , suspecting a Spartan ploy and having already begun the work of construction , Athens employed subterfuge to delay the wheels of diplomacy until she could finish them . In 464 BC , suffering another Helot rebellion and failing to make progress in the siege against their stronghold Ithome , Sparta had asked for Athens ' aid along with its other allies . But after a " considerable force " arrived from Athens under the command of Cimon , Sparta , fearing the " unorthodox " politics of Athens and the possibility of her supporting the enslaved Helots rather than fighting them , sent the Athenian contingent home while keeping on the rest of her allies . Deeply offended by these Spartan interferences and insults , Athens was increasingly willing to support discord within the Peloponnesian League and took Megara into its protection during its border dispute with the Spartan - allied Corinth , leading to open war with Corinth but not Sparta herself . The battle . When the Phocians made war on the cities of Doris — the traditional homeland of Doric Greeks — the Doric Sparta sent a relief force under the command of Nicomedes , son of Cleombrotus , acting as regent for his under - age nephew , King Pleistoanax . An army of 1 , 500 Spartan hoplites with 10 , 000 of their allies entered Boeotia and compelled the submission of Phocis . Athens , already contemptuous of Spartan treatment and now suspecting her of negotiating with factions within the city to undermine democracy and prevent the construction of the Long Walls , maneuvered to cut off the Spartan army isolated in Boeotia . Facing either transport through waters controlled by the Athenian navy or a difficult march through the Geraneia mountain passes held by Athenian soldiers supported from Megara , the Spartans decided to wait either for the opening of a safe route home or an outright Athenian assault . Meeting the Spartans at Tanagra , Athens fielded " their whole army , supported by 1 , 000 troops from Argos and by contingents from their other allies , making up altogether a force of 14 , 000 men . " Although both sides sustained " great losses , " the Spartans were victorious and now able to return home through the mountain passes of the Isthmus . Aftermath . Two months later , the Athenians regrouped and defeated Thebes at the Battle of Oenophyta and took control of Boeotia , taking down the wall the Spartans had built . With the victory the Athenians also occupied Phocis , the original source of the conflict and the Opuntian Locris .