d 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.

Besides the principal ports of Ravenna and Misenum, Augustus stationed a
very considerable force at Frejus, on the coast of Provence, forty ships in
the Euxine, with 3000 soldiers; a fleet to preserve the communication
between Gaul and Britain, another near Alexandria, and a great number of
smaller vessels on the Rhine and the Danube. As soon as the Romans had
constant and regular fleets, instead of the legionary soldiers, who used to
fight at sea as well as at land, a separate band of soldiers were raised
for the sea service, who were called Classiarii; but this service was
reckoned less honourable than that of the legionary soldiers.

The period at which we are arrived seems a proper one to take a general
view of the commerce of the Roman empire; though, in order to render this
view more complete, it will be necessary in many instances to anticipate
the transactions posterior to the reign of Augustus. We shall, therefore,
in the first place, give a statement of the extent of the Roman empire when
it