* The Roman Republic is founded, traditionally dated to 509 BC.
* The exiled Roman king, Tarquin the Proud, attempts to regain his throne, but is defeated by the Romans at the Battle of Silva Arsia.
* The Battle of Boium, part of the Latin War, is fought between the Romans and the Volsci.
* The Battle of Aricia is fought between the Romans and the Latins.
* The Battle of Regillum is fought between the Romans and the Sabines.