nt scene of war,
a single legion maintained the domestic tranquillity of each of those
great provinces. Even Italy was not left destitute of a military force.
Above twenty thousand chosen soldiers, distinguished by the titles
of City Cohorts and Praetorian Guards, watched over the safety of the
monarch and the capital. As the authors of almost every revolution that
distracted the empire, the Praetorians will, very soon, and very loudly,
demand our attention; but, in their arms and institutions, we cannot
find any circumstance which discriminated them from the legions, unless
it were a more splendid appearance, and a less rigid discipline. [65]

[Footnote 65: Tacitus (Annal. iv. 5) has given us a state of the
legions under Tiberius; and Dion Cassius (l. lv. p. 794) under Alexander
Severus. I have endeavored to fix on the proper medium between these two
periods. See likewise Lipsius de Magnitudine Romana, l. i. c. 4, 5.]

The navy maintained by the emperors might seem inadequate to their
greatness; but it was fully sufficient for every useful purpose of
government. The ambition of the Romans was confined to the land; nor was
that warlike people ever actuated by the enterprising spirit which had
prompted the navigators of Tyre, of Carthage, and even of Marseilles, to
enlarge the bounds of the world, and to explore the most remote coasts
of the ocean. To the Romans the ocean remained an object of terror
rather than of curiosity; [66] the whole extent of the Mediterranean,
after the destruction of Carthage, and the extirpation of the pirates,
was included within their provinces. The policy of the emperors was
directed only to preserve the peaceful dominion of that sea, and to
protect the commerce of their subjects. With these moderate views,
Augustus stationed two permanent fleets in the most convenient ports of
Italy, the one at Ravenna, on the Adriatic, the other at Misenum, in
the Bay of Naples. Experience seems at length to have convinced the
ancients, that as soon as their galleys exceeded two, or at the most
three ranks of oars, they were suited rather for vain pomp than for
real service. Augustus himself, in the victory of Actium, had seen the
superiority of his own light frigates (they were called Liburnians) over
the lofty but unwieldy castles of his rival. [67] Of these Liburnians he
composed the two fleets of Ravenna and Misenum, destined to command, the
one the eastern, the other the western division of the Medit