The Siege of Veii
After nearly a decade of failure, Rome decided to take an Etruscan city by digging a secret tunnel beneath its walls.

Unknown — "Marble relief fragment with scenes from the Trojan War" (1st half of 1st century CE), public domain
Ten years of deadlock.
The wealthy Etruscan city of Veii stood just twelve miles from Rome. For almost a decade, the Romans battered its walls — winning battles, then losing them, but never breaking in. Veii’s defenders taunted them from the ramparts.
A tunnel in the dark.
With open assault failing, the Romans tried a new tactic. Under the command of Marcus Furius Camillus, they began digging a tunnel — right beneath Veii’s massive citadel. Ancient sources say Roman soldiers burst up inside the city’s temple of Juno, catching the defenders mid-sacrifice.
Rome transforms overnight.
With Veii fallen, Rome annexed its lands and riches. The balance of power in central Italy flipped — and Rome learned that patience, and a bit of engineering nerve, could conquer what brute force could not.
The Romans’ patience and engineering broke Veii — not their swords. This victory more than doubled Rome’s territory overnight, and set the model for sieges for centuries.