The Battle of Veii, also known as the Siege of Veii is a battle of ancient Rome, approximately dated at 396 BC. The main source about it is Livy's Ab Urbe Condita.
The Romans were led by a dictator (in the Roman Republic, this was an emergency general rather than a tyrant) named Marcus Furius Camillus. Their opponent, the Etruscan city of Veii, a large city close to Rome had engaged the Romans in a long and inconclusive war during which it had often been under siege. In order to break the siege once and for all, a tunnel was reputedly built beneath the city.
Livy describes the scene with the Veientines holed up in their city, the main Roman force encamped outside and a second force set to attack from within via the tunnel. After this prayer from Camillus,
Pythian Apollo, guided and inspired by thy will I go forth to destroy the city of Veii, and a tenth part of its spoils I devote to thee. Thee too, Queen Juno, who now dwellest in Veii, I beseech, that thou wouldst follow us, after our victory, to the City which is ours and which will soon be thine, where a temple worthy of thy majesty will receive thee. He attacked from all sides.