distinguished from the legions.

The emperor was, of course, head of all the fleets, which were, each
of them, commanded by a prefect and sub-prefect appointed by him; and
if we may judge from the recorded promotions we have, it would seem
that the Misenate prefect ranked before the Ravennate and both before
the Provincial. But in the general military system the navy stood
lowest in respect of pay and position. The fleets were manned by freed
men and foreigners who could not obtain citizenship until after
twenty-six years' service. We find Claudius employing the marines of
the _Classis Ravennas_ to drain lake Fucinus, and it was probably
Vespasian who formed the Legion II. _Adjutrix_ from the Ravennate,
even as Nero had formed Legion I. _Adjutrix_ from the Misenate
marines.

The Ravenna that Augustus thus chose to be the great base and port of
his fleet in the eastern sea was, as we have seen, a place built upon
piles in the midst of the marshes, impregnable from the land, and,
because impregnable, able, whenever it was in dispute, to command the
narrow pass between the mountains and the sea that was the gate of
Italy and Cisalpine Gaul. Such a place, situated as it was upon the
western shore of that sea which was the fault between East and West,
was eminently suitable for the great purpose of the emperor. Pliny[1]
indeed would seem to tell us that from time immemorial Ravenna had
possessed a small port; but such a place, well enough for the small
traders of those days, could not serve usefully the requirements of a
great fleet. Therefore the first act of Augustus, when he had chosen
Ravenna as his naval base, was the construction of a proper port and
harbour, and these came to be named, after the fleet they served and
accommodated, Classis. Classis was situated some two and a half miles