The sack of Rome (390 B.C.) was the worst recorded disaster in the history of the early Roman Republic, and saw a Gallic war band led by Brennus capture and sack most of the city, after winning an easy victory on the Allia. ... They were only able to raise a small army, which was easily defeated on the Allia.
In 390 B.C. the Battle of Allia took place. It was fought between Rome (the Republic) and the Senones, a Gallic tribe that entered through Northern Italian territories. The battle started 20 miles away from the city of Rome but the Senones managed to route the fight closer to the city. Once in the city of Rome, it was sacked.
