One of the most considerable revolutions in the maritime and commercial affairs of Rome, was brought about by the battle of Actium. The fleet of Anthony was composed chiefly of ships belonging to the Egyptians, Tyrians, and other nations of the east, and amounted, according to some accounts, to 200 sail, whereas the fleet of Augustus consisted of 400 sail. Other authors estimate them differently; but all agree that the ships of Anthony were much larger, stronger, and loftier, than those of Caesar: they were consequently more unwieldy. We have the express testimony of Plutarch, that it was principally this victory which convinced Caesar of the advantages and extraordinary use of the Liburnian ships; for though they had been employed before this time in the Roman fleet, yet they had never been so serviceable in any previous battle. Augustas, therefore, as well as most of the succeeding emperors of Rome, scarcely built any other ships but those according to the Liburnian model. One of the first objects of Augustus, after he had obtained the empire, was to secure the command of the sea: he made use of the ships which he had captured from Anthony to keep the people of Gaul in subjection; and he cleared the Mediterranean of the pirates which infested it and obstructed commerce. He formed two fleets, one at Ravenna, and the other at Misenum; the former to command the eastern, the latter the western division of the Mediterranean: each of these had its own proper commanders, and to each was attached a body of several thousand mariners. Ravenna, situated on the Adriatic, about ten or twelve miles from the most southern of the seven mouths of the Po, was not a place of much consequence till the age of Augustus: that emperor, observing its advantages, formed at the distance of about three miles from the old town and nearer the sea, a capacious harbour, capable of containing 250 ships of war. The establishment was on a large and complete scale, consisting of arsenals, magazines, barracks, and houses for the ship-carpenters, &c.: the principal canal, which was also formed by Augustus, and took its name from him, carried the waters of the river through the middle of Ravenna to the entrance of the harbour. The city was rendered still stronger by art than nature had formed it. As early as the fifth or sixth centuries of the Christian era the port was converted, by the retreat of the sea, into dry ground, and a grove of pines grew where the Roman fleet had anchored.