Allia, a stream flowing into the *Tiber on the east bank, 18 km. (11 mi.) north of Rome (probably modern Fosso della Bettina), where the Romans confronted, and were overwhelmed by, a Gallic war-band (18 July 390 bce), resulting in the capture of Rome itself. The related but differing accounts of the battle in our sources are probably later reconstructions. See also brennus (1).