First Gallic Invasion of Italy and sack of Rome

The First Gallic Invasion of Italy of 390 B.C. was a pivotal event in the history of the Roman Republic and saw the city occupied and sacked for the last time in eight hundred years.
The battle of the Allia (18 July 390 B.C.) was one of the most embarrassing defeats in Roman history, and left the city defenceless in the face of a Gallic war band.
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
The battle of the Trausian Plain (c.390-384 B.C.) probably saw an Etruscan army from the city of Caere defeat all or part of the Gallic war band that was responsible for the sack of Rome