The wars of Rome would by 390 BC involve a new enemy from outside the local region. The Celts from the Po Valley under the leadership of Brennus had marched southward and after a failed embassy from Rome decided to invade Roman territory. The Romans were defeated in the Battle of the Allia and Rome itself was now threatened. Camillus, the former colleague of Valerius, was recalled from exile (he had been exiled in 391 BC for his conduct in the aftermath of his triumph and victory against the Veii) and appointed dictator. Camillus appointed Valerius as his magister equitum (co-dictator). Camillus and Valerius succeeded with pushing back the Gauls who had by then captured all of Rome with the exception of the Capitoline. They stayed in office after this victory to stop a proposal of abandoning Rome and for Camillus to celebrate a triumph.