In the following period Rome experiences an unexpected prosperity because of its unique location on the Tiber, which was navigable from Ostia up to the Tiber- island in Rome. Ostia's fate was inextricably bounded up with Rome.
During the fourth century BC Rome gets invoIved in several naval wars. From now on Ostia starts to play a important role as a military harbour. When, in 267 BC Rome installed a new naval magistracy, one of the officials was permanently seated in Ostia (Lydus).