The only serious war to be feared within the empire itself was a civil war, begun by some aspiring leader when his chance seemed strong of ousting the existing emperor or of succeeding to his throne.  Four years from the date at which we have placed ourselves such a war actually did break out.  Nero was driven from the throne in favour of Galba, and the history of the year following is the history of Otho murdering Galba, Vitellius overthrowing Otho, and Vespasian in his turn overthrowing Vitellius.  Yet all this is but the story of one entirely exceptional year, the famous “year of four emperors.”  Take out that year from the imperial history; count a hundred years before and more than a hundred years after, and it would be impossible to find in the history of the world any period at which peace, and probably contentment, was so widely and continuously spread.  Think of all the countries which have just been enumerated as lying within the Roman border; then imagine that, with the exception of one year of general commotion, two or three provincial and local revolts, and occasional irruptions and retaliations upon the frontier, they have all been free from war and its havoc ever since the year 1700.  In our year of grace 64, although the throne is occupied by a vicious emperor suffering from megalomania and enormous self-conceit, the empire is in full enjoyment of its pax Romana.

Another glance at the map will show how secure this internal peace was felt to be.  The Roman armies will be found almost entirely upon the frontiers.  It was, of course, imperative that there should be strong forces in such positions—­in Britain carrying out the annexation; on the Rhine and Danube defending against huge-bodied, restless Germans and their congeners; on the Euphrates to keep off the nimble and dashing Parthian horse and foot; in Upper Egypt to guard against the raids of “Fuzzy-Wuzzy “; in the interior of Tunis or Algeria to keep the nomad Berber tribes in hand.  In such places were the Roman legions and their auxiliary troops regularly kept under the eagles, for there lay their natural work, and there do we find them quartered generation after generation.

It is, of course, true that they might be employed inwards as well as outwards; but it must be manifest that, if there had been any widespread disaffection, any reasonable suspicion that serious revolts might happen, there would have been many other large bodies of troops posted in garrison throughout the length and breadth of the provinces.  In point of fact the whole Roman military force can scarcely have amounted to more than 320,000 men, while the navy consisted of two small fleets of galleys, one regularly posted at Misenum at the entrance to the Bay of Naples, the other at Ravenna on the Adriatic.  To these we may add a flotilla of boats operating on the Lower Rhine and the neighbouring coasts.  Except during the year of civil war the two fleets have practically no history.  They enjoyed the advantage of having