The only accession which the Roman empire received, during the first century of the Christian Æra, was the province of Britain. In this single instance, the successors of Cæsar and Augustus were persuaded to follow the example of the former, rather than the precept of the latter. The proximity of its situation to the coast of Gaul seemed to invite their arms; the pleasing though doubtful intelligence of a pearl fishery, attracted their avarice; and as Britain was viewed in the light of a distinct and insulated world, the conquest scarcely formed any exception to the general system of continental measures. After a war of about forty years, undertaken by the most stupid, maintained by the most dissolute, and terminated by the most timid of all the emperors, the far greater part of the island submitted to the Roman yoke. The various tribes of Britain possessed valor without conduct, and the love of freedom without the spirit of union. They took up arms with savage fierceness; they laid them down, or turned them against each other, with wild inconsistency; and while they fought singly, they were successively subdued. Neither the fortitude of Caractacus, nor the despair of Boadicea, nor the fanaticism of the Druids, could avert the slavery of their country, or resist the steady progress of the Imperial generals, who maintained the national glory, when the throne was disgraced by the weakest, or the most vicious of mankind. At the very time when Domitian, confined to his palace, felt the terrors which he inspired, his legions, under the command of the virtuous Agricola, defeated the collected force of the Caledonians, at the foot of the Grampian Hills; and his fleets, venturing to explore an unknown and dangerous navigation, displayed the Roman arms round every part of the island. The conquest of Britain was considered as already achieved; and it was the design of Agricola to complete and insure his success, by the easy reduction of Ireland, for which, in his opinion, one legion and a few auxiliaries were sufficient. The western isle might be improved into a valuable possession, and the Britons would wear their chains with the less reluctance, if the prospect and example of freedom were on every side removed from before their eyes.

But the superior merit of Agricola soon occasioned his removal from the government of Britain; and forever disappointed this rational, though extensive scheme of conquest. Before his departure, the prudent general had provided for security as well as for dominion. He had observed, that the island is almost divided into two unequal parts by the opposite gulfs, or, as they are now called, the Friths of Scotland. Across the narrow interval of about forty miles, he had drawn a line of military stations, which was afterwards fortified, in the reign of Antoninus Pius, by a turf rampart, erected on foundations of stone. This wall of Antoninus, at a small distance beyond the modern cities of Edinburgh and Glasgow, was fixed as the limit of the Roman province. The native Caledonians preserved, in the northern extremity of the island, their wild independence, for which they were not less indebted to their poverty than to their valor. Their incursions were frequently repelled and chastised; but their country was never subdued. The masters of the fairest and most wealthy climates of the globe turned with contempt from gloomy hills, assailed by the winter tempest, from lakes concealed in a blue mist, and from cold and lonely heaths, over which the deer of the forest were chased by a troop of naked barbarians.

Such was the state of the Roman frontiers, and such the maxims of Imperial policy, from the death of Augustus to the accession of Trajan. That virtuous and active prince had received the education of a soldier, and possessed the talents of a general. The peaceful system of his predecessors was interrupted by scenes of war and conquest; and the legions, after a long interval, beheld a military emperor at their head. The first exploits of Trajan were against the Dacians, the most warlike of men, who dwelt beyond the Danube, and who, during the reign of Domitian, had insulted, with impunity, the Majesty of Rome. To the strength and fierceness of barbarians they added a contempt for life, which was derived from a warm persuasion of the immortality and transmigration of the soul. Decebalus, the Dacian king, approved himself a rival not unworthy of Trajan; nor did he despair of his own and the public fortune, till, by the confession of his enemies, he had exhausted every resource both of valor and policy. This memorable war, with a very short suspension of hostilities, lasted five years; and as the emperor could exert, without control, the whole force of the state, it was terminated by an absolute submission of the barbarians. The new province of Dacia, which formed a second exception to the precept of Augustus, was about thirteen hundred miles in circumference. Its natural boundaries were the Niester, the Teyss or Tibiscus, the Lower Danube, and the Euxine Sea. The vestiges of a military road may still be traced from the banks of the Danube to the neighborhood of Bender, a place famous in modern history, and the actual frontier of the Turkish and Russian empires.