The Senones' defeat of Roman forces at the Allia led directly to the sack of Rome, marking one of the gravest military disasters in early Roman history.
Key Facts
- Date (approx.)
- c. 387 BC
- Distance from Rome
- 11 Roman miles (16 km) north of Rome
- Gallic tribe
- Senones
- Gallic commander
- Brennus
- Battle site
- Confluence of Tiber river and Allia brook
- Dies Alliensis
- Marked as an ill-omened dies religiosus in Roman calendar
Location
Cause → Event → Consequence
The Senones, a Gallic tribe led by Brennus, invaded Northern Italy and advanced southward. The Roman Republic mobilized forces to intercept them before they could reach Rome, leading to a confrontation at the Allia brook, a tributary of the Tiber approximately 16 kilometres north of the city.
At the confluence of the Tiber and the Allia brook, the Roman forces engaged the Senones in battle around 387 BC. The Romans were decisively routed, suffering a catastrophic defeat that left the road to Rome undefended and the city exposed to the advancing Gallic army.
Following their victory, the Senones sacked Rome itself, an event of lasting trauma in Roman memory. The day of the battle was commemorated as the dies Alliensis, treated as an ill-omened dies religiosus on which public and ritual activity was avoided, though the tradition is attested only from the 1st century BC.
Belligerents & Mobilization Analysis
Side A
1 belligerent
Side B
1 belligerent
Brennus.