432 BC

Centuries:	6th century BC · 5th century BC · 4th century BC
Decades:	460s BC 450s BC 440s BC 430s BC 420s BC 410s BC 400s BC
Years:	435 BC 434 BC 433 BC 432 BC 431 BC 430 BC 429 BC

Events

Sparta calls and hosts a conference of the Peloponnesian League. The conference is attended by Athenian representatives as well as members of the League. Following arguments by Corinth against Athens, a majority of the League members vote to declare that the Athenians had broken the peace.
The Athenian admiral, Phormio, continues the siege of Potidaea by blocking the entrance to the Gulf of Corinth. Meanwhile an Athenian fleet, led by Archestratus, sails for Potidaea. However, instead of attacking Potidaea, they attack the Macedonians under Perdiccas who have allied with the Potidaeans. The Athenians capture Therma (modern Thessalonica) and then go on to besiege Pydna. However, as the Athenians are besieging Pydna, they receive news that Corinth has sent a force under the command of Aristeus to support Potidaea. In response, Athens sends more troops and ships under the command of Hipponicus. The combined Athenian force sails to Potidaea and lands there. In the ensuing Battle of Potidaea, the Athenians are victorious against Corinth and its allies.

The Greek colony of Heraclea in Southern Italy is founded by colonists from Tarentum and Thurii.

Meton of Athens, a Greek mathematician and astronomer, calculates accurately the comparative chronology of the solar and lunar cycles. As a result, he introduces the 19-year Metonic cycle into the Athenian calendar as a method of calculating dates. Working with Euctemon, he observes the summer solstice on 27 June.