The Battle of Silva Arsia was a battle in 509 BC between the republican forces of ancient Rome and Etruscan forces of Tarquinii and Veii led by the deposed Roman king Lucius Tarquinius Superbus. The battle took place near the Silva Arsia (the Arsian forest) in Roman territory, and resulted in victory to Rome but the death of one of her consuls, Lucius Junius Brutus.

The battle was one of a number of attempts by Tarquin to regain the throne, and can also be seen as part of the ongoing conflict between the Etruscan cities and the expanding Roman state. The battle forms part of Rome's early history, which is to a large degree legendary.

Publius Valerius Poplicola or Publicola (died 503 BC) was one of four Roman aristocrats who led the overthrow of the monarchy, and became a Roman consul, the colleague of Lucius Junius Brutus in 509 BC, traditionally considered the first year of the Roman Republic.