Peace of Nicias (421 BC): The Fragile Truce of Athens and Sparta

The Peace of Nicias was a treaty agreed in the spring of 421 BC between Athens and Sparta, ending the first ten years of the Peloponnesian War. Named after the Athenian statesman Nicias, it was meant to last fifty years. In practice it was an uneasy truce: several of Sparta’s allies refused to accept it, key terms were never carried out, and within a few years the two powers were at war again.

Background: both sides seek peace

By 422 BC both sides were exhausted. Athens had suffered the plague and a heavy defeat at Delium in 424 BC, and the Spartan commander Brasidas had taken its key colony of Amphipolis in the north Aegean. Sparta, for its part, desperately wanted back the men captured at Pylos and Sphacteria in 425 BC, and feared helot revolts while the Athenians held Pylos.

In 422 BC Cleon, the leading Athenian advocate of war, and Brasidas, Sparta’s most aggressive general, were both killed in a battle outside Amphipolis. Their deaths removed the main obstacles to a settlement. Sparta also faced the expiry of its old treaty with Argos, a powerful rival in the Peloponnese, and wanted a free hand.

In Athens, Nicias, a wealthy and cautious general, led the case for peace. In Sparta the king Pleistoanax, who had been recalled from a long exile, also pressed for agreement. Negotiations ran through the winter of 422/421 BC.

The terms

Thucydides preserves the text of the treaty. It was concluded immediately after the City Dionysia festival in Athens, in the spring of 421 BC. Its main provisions were:

• Peace for fifty years between Athens and Sparta and their allies, by land and sea, with disputes settled by legal means.
• Free access for all to the common sanctuaries, and independence for the shrine of Apollo at Delphi.
• Sparta to return Amphipolis to Athens. Several cities in the Chalcidice were to be autonomous but to keep paying Athens the tribute set in the time of Aristides.
• Athens to give back Pylos, Cythera, Methana and other places it had taken.
• Both sides to release all prisoners, including the men taken on Sphacteria.

Seventeen leading men from each side swore the oaths, which were to be renewed every year. Copies were set up on stone slabs at Olympia, Delphi, the Isthmus of Corinth, the Acropolis of Athens and the shrine of Apollo at Amyclae near Sparta.

Why it failed

According to Plutarch, lots were drawn to decide which side should return its gains first, and the lot fell on Sparta. But Sparta’s allies would not cooperate. Corinth, Boeotia, Elis and Megara refused to sign, objecting to terms that ignored their interests. The Spartan commander in Thrace, Clearchus, did not hand over Amphipolis, saying the local people would not allow it.

Fearing that the peace was unravelling, Athens and Sparta concluded a separate fifty-year defensive alliance soon afterwards, and Athens released the Sphacteria prisoners. Athens, however, kept Pylos because Amphipolis had not been returned.

Distrust grew. The young Athenian politician Alcibiades, who resented that Sparta had negotiated through Nicias rather than through him, persuaded Athens in 420 BC to ally with Argos, Elis and Mantinea. In 418 BC this coalition was defeated by the Spartan king Agis II at the Battle of Mantinea, which Thucydides calls the greatest battle fought between Greeks for a very long time.

Formally the peace still stood, but neither side respected it. In 414 BC Athenian ships joined Argive raids on the coast of Laconia, which Thucydides describes as an open breach of the treaty. In 413 BC Sparta resumed full-scale war by occupying Decelea in Attica, while Athens was heavily committed to the Sicilian Expedition.

Key people

• Nicias (c. 470-413 BC): a rich Athenian general known for caution and piety. He later opposed the Sicilian Expedition but was made one of its commanders and was executed by the Syracusans in 413 BC.
• Pleistoanax (died 409/408 BC): the Agiad king of Sparta, who supported peace after returning from nearly twenty years of exile.
• Alcibiades (c. 450-404 BC): Nicias’ rival, whose diplomacy helped undermine the peace.

Timeline

• 424 BC: Athenian defeat at Delium; Brasidas takes Amphipolis.
• 422 BC: Cleon and Brasidas are killed at Amphipolis.
• 421 BC, spring: the Peace of Nicias is sworn, followed by an Athenian-Spartan alliance.
• 420 BC: Athens allies with Argos, Elis and Mantinea.
• 418 BC: Sparta defeats the coalition at Mantinea.
• 414 BC: Athenian raids on Laconia openly breach the treaty.
• 413 BC: Sparta fortifies Decelea and the war resumes in full.

Legacy

Thucydides argued that it was wrong to treat the peace as a real end to the war. He insisted that the whole period from 431 to 404 BC formed a single 27-year conflict, interrupted only by a suspicious truce. Most modern historians follow his view.

The peace also left a cultural mark. Aristophanes’ comedy Peace, which celebrates the end of the war, was staged at the City Dionysia in 421 BC, just days before the treaty was concluded, and won second prize.

Why it matters

The Peace of Nicias showed how hard it is to end a war when allies’ interests are ignored and the main rivals remain deeply suspicious of each other. Its failure opened the way to the Sicilian disaster and the final defeat of Athens, and it remains a classic example of a peace that merely paused a conflict.