ALLIA, a river of Italy, in the Sabine territory, which running down a very deep channel from the mountains of Crustumium, mixes with the Tiber 40 miles from Rome; famous for the great slaughter of the Romans, by the Gauls under Brennus, when 40,000 Romans were killed or put to flight; hence Alliensis dies, an unlucky day (Virgil, Ovid, Lucan). Our ancestors, says Cicero, deemed the day of the fight of Allia more fatal than that of taking the city.