Allia, Battle of the, Italy, 390 B.C.

The Battle of the Allia was fought c. 387 BC between the Senones – a Gallic tribe led by Brennus, who had invaded Northern Italy – and the Roman Republic. The battle was fought at the confluence of the Tiber river and Allia brook, 11 Roman miles (16 km, 10 mi) north of Rome. The Romans were routed and subsequently Rome was sacked by the Senones. The dies Alliensis ('Day of the Allia') was regarded as an ill-omened day in the Roman calendar, and treated as a dies religiosus on which public and ritual activity was avoided. Although later authors such as Livy present it as a lasting civic taboo, the tradition is only attested from the 1st century BC and likely reflects later reconstruction rather than continuous observance from the 4th to the 1st century AD.