When Britain was thus dismembered from the empire, its importance was sensibly felt, and its loss sincerely lamented. The Romans celebrated, and perhaps magnified, the extent of that noble island, provided on every side with convenient harbors; the temperature of the climate, and the fertility of the soil, alike adapted for the production of corn or of vines; the valuable minerals with which it abounded; its rich pastures covered with innumerable flocks, and its woods free from wild beasts or venomous serpents. Above all, they regretted the large amount of the revenue of Britain, whilst they confessed, that such a province well deserved to become the seat of an independent monarchy.[1249] during the space of seven years it was possessed by Carausius; and fortune continued propitious to a rebellion supported with courage and ability. The British emperor defended the frontiers of his dominions against the Caledonians of the North, invited, from the continent, a great number of skilful artists, and displayed, on a variety of coins that are still extant, his taste and opulence. Born on the confines of the Franks, he courted the friendship of that formidable people, by the flattering imitation of their dress and manners. The bravest of their youth he enlisted among his land or sea forces; and, in return for their useful alliance, he communicated to the barbarians the dangerous knowledge of military and naval arts. Carausius still preserved the possession of Boulogne and the adjacent country. His fleets rode triumphant in the channel, commanded the mouths of the Seine and of the Rhine, ravaged the coasts of the ocean, and diffused beyond the columns of Hercules the terror of his name. Under his command, Britain, destined in a future age to obtain the empire of the sea, already assumed its natural and respectable station of a maritime power.[1250]
By seizing the fleet of Boulogne, Carausius had deprived his master of the means of pursuit and revenge. And when, after a vast expense of time and labor, a new armament was launched into the water,[1251] the imperial troops, unaccustomed to that element, were easily baffled and defeated by the veteran sailors of the usurper. This disappointed effort was soon productive of a treaty of peace. Diocletian and his colleague, who justly dreaded the enterprising spirit of Carausius, resigned to him the sovereignty of Britain, and reluctantly admitted their perfidious servant to a participation of the Imperial honors.[1252] but the adoption of the two Caesars restored new vigor to the Romans arms; and while the Rhine was guarded by the presence of Maximian, his brave associate Constantius assumed the conduct of the British war. His first enterprise was against the important place of Boulogne. A stupendous mole, raised across the entrance of the harbor, intercepted all hopes of relief. The town surrendered after an obstinate defence; and a considerable part of the naval strength of Carausius fell into the hands of the besiegers. During the three years which Constantius employed in preparing a fleet adequate to the conquest of Britain, he secured the coast of Gaul, invaded the country of the Franks, and deprived the usurper of the assistance of those powerful allies.
Before the preparations were finished, Constantius received the intelligence of the tyrant's death, and it was considered as a sure presage of the approaching victory. The servants of Carausius imitated the example of treason which he had given. He was murdered by his first minister, Allectus, and the assassin succeeded to his power and to his danger. But he possessed not equal abilities either to exercise the one or to repel the other.
He beheld, with anxious terror, the opposite shores of the continent already filled with arms, with troops, and with vessels; for Constantius had very prudently divided his forces, that he might likewise divide the attention and resistance of the enemy. The attack was at length made by the principal squadron, which, under the command of the praefect Asclepiodatus, an officer of distinguished merit, had been assembled in the north of the Seine. So imperfect in those times was the art of navigation, that orators have celebrated the daring courage of the Romans, who ventured to set sail with a side-wind, and on a stormy day. The weather proved favorable to their enterprise. Under the cover of a thick fog, they escaped the fleet of Allectus, which had been stationed off the Isle of Wight to receive them, landed in safety on some part of the western coast, and convinced the Britons, that a superiority of naval strength will not always protect their country from a foreign invasion. Asclepiodatus had no sooner disembarked the imperial troops, then he set fire to his ships; and, as the expedition proved fortunate, his heroic conduct was universally admired. The usurper had posted himself near London, to expect the formidable attack of Constantius, who commanded in person the fleet of Boulogne; but the descent of a new enemy required his immediate presence in the West. He performed this long march in so precipitate a manner, that he encountered the whole force of the praefect with a small body of harassed and disheartened troops. The engagement was soon terminated by the total defeat and death of Allectus; a single battle, as it has often happened, decided the fate of this great island; and when Constantius landed on the shores of Kent, he found them covered with obedient subjects. Their acclamations were loud and unanimous; and the virtues of the conqueror may induce us to believe, that they sincerely rejoiced in a revolution, which, after a separation of ten years, restored Britain to the body of the Roman empire.[1253]
Part II
Britain had none but domestic enemies to dread; and as long as the governors preserved their fidelity, and the troops their discipline, the incursions of the naked savages of Scotland or Ireland could never materially affect the safety of the province.
The peace of the continent, and the defence of the principal rivers which bounded the empire, were objects of far greater difficulty and importance. The policy of Diocletian, which inspired the councils of his associates, provided for the public tranquility, by encouraging a spirit of dissension among the barbarians, and by strengthening the fortifications of the Roman limit. In the East he fixed a line of camps from Egypt to the Persian dominions, and for every camp, he instituted an adequate number of stationary troops, commanded by their respective officers, and supplied with every kind of arms, from the new arsenals which he had formed at Antioch, Emesa, and Damascus.[1254] nor was the precaution of the emperor less watchful against the well-known valor of the barbarians of Europe. From the mouth of the Rhine to that of the Danube, the ancient camps, towns, and citidels, were diligently reestablished, and, in the most exposed places, new ones were skilfully constructed: the strictest vigilance was introduced among the garrisons of the frontier, and every expedient was practised that could render the long chain of fortifications firm and impenetrable.[1255] a barrier so respectable was seldom violated, and the barbarians often turned against each other their disappointed rage. The Goths, the Vandals, the Gepidae, the Burgundians, the Alemanni, wasted each other's strength by destructive hostilities: and whosoever vanquished, they vanquished the enemies of Rome. The subjects of Diocletian enjoyed the bloody spectacle, and congratulated each other, that the mischiefs of civil war were now experienced only by the barbarians.[1256]
1249
Panegyr. Vet v 11, vii. 9. The orator Eumenius wished to exalt the glory of the hero (Constantius) with the importance of the conquest. Notwithstanding our laudable partiality for our native country, it is difficult to conceive, that, in the beginning of the fourth century England deserved all these commendations. A century and a half before, it hardly paid its own establishment.
1250
As a great number of medals of Carausius are still preserved, he is become a very favorite object of antiquarian curiosity, and every circumstance of his life and actions has been investigated with sagacious accuracy. Dr. Stukely, in particular, has devoted a large volume to the British emperor. I have used his materials, and rejected most of his fanciful conjectures.
1251
When Mamertinus pronounced his first panegyric, the naval preparations of Maximian were completed; and the orator presaged an assured victory. His silence in the second panegyric might alone inform us that the expedition had not succeeded.
1252
Aurelius Victor, Eutropius, and the medals, (Pax Augg.) inform us of this temporary reconciliation; though I will not presume (as Dr. Stukely has done, Medallic History of Carausius, p. 86, &c) to insert the identical articles of the treaty.
1253
With regard to the recovery of Britain, we obtain a few hints from Aurelius Victor and Eutropius.
1255
Zosim. l. i. p. 3. That partial historian seems to celebrate the vigilance of Diocletian with a design of exposing the negligence of Constantine; we may, however, listen to an orator: «Nam quid ego alarum et cohortium castra percenseam, toto Rheni et Istri et Euphraus limite restituta.» Panegyr. Vet. iv. 18.
1256
Ruunt omnes in sanguinem suum populi, quibus ron contigilesse Romanis, obstinataeque feritatis poenas nunc sponte persolvunt. Panegyr. Vet. iii. 16. Mamertinus illustrates the fact by the example of almost all the nations in the world.