The naval battle of Cumae (or Cyme) of 474 BC saw a combined fleet from Syracuse and Cumae defeat an Etruscan fleet in a battle fought in the bay of Naples.
The Greek city of Cyme (Cumae in Latin) had been founded in the 8th century BC in an area towards the southern limits of Etruscan power. The southern Etruscans had been defeated by the Cumaeans in 524 and 504, but still remained a powerful force. In 474 BC they were able to bring together a fleet that was able to directly threaten Cumae.
The Cimaeans send a delegation to Hieron, Tyrant of Syracuse, asking for military assistance. Hieron sent a fleet of triremes to Cumae. The Syracusan fleet was able to reach Cumea, where it united with the local forces. The combined fleet then put out to sea and defeated the Etruscans in a great sea battle. This was later commemorated in Pindar's first Pythian Ode, an account that places the battle off Cumae.
In the long term the battle helped complete the decline of Etruscan power in southern Italy, leaving the area open to incursions by Samnites and Romans. In the short term it helped to establish Hieron's power in the southern Tyrrhenian Sea.