Athens developed a powerful empire after the Persian Wars, which was greatly resented by the Spartans. It was only a matter of time before conflict ensued. In 457 BC, the Spartans defeated the Athenians at Tanagra.
In 431 BC, war began in earnest when the Spartans ravaged Attica. The whole Greek world was drawn into the conflict. Athens controlled the seas while Sparta was dominant on land but could not penetrate Athens' land defences.
In 425 BC, the Athenians seized Pylos and captured an elite Spartan force at Sphacteria. The Spartan and Athenian commanders both died in battle at Amphipolis, so a fifty years' peace was agreed in 421 BC.
The war was renewed in 419 BC when the Athenians attacked Sparta's ally Epidauros, but were defeated by the Spartans at Mantinea. Athens then lost half her fleet in a disastrous expedition against Syracuse in 415-413 BC.
An Athenian victory in a sea battle off the Cynossema promontory in 411 BC restored the balance of power. Sparta sued for peace, but Athens decided to continue the war.
The Spartans made an alliance with Persia and rebuilt their fleet with Persian money. When they destroyed the Athenian navy at Aegospotami in 405 BC, the war was effectively over. Athens was starved into surrender one year later.
