From Sleswick and the shores of the Northern Sea we must pass, before opening our story, to a land which, dear as it is now to Englishmen, had not as yet been trodden by English feet. The island of Britain had for nearly four hundred years been a province of the Empire. A descent of Julius Caesar revealed it (BC 55) to the Roman world, but nearly a century elapsed before the Emperor Claudius attempted its definite conquest. The victories of Julius Agricola (AD 78-84) carried the Roman frontier to the Firths of Forth and Clyde, and the work of Roman civilization followed hard upon the Roman sword. The conquered population was grouped in great cities such as York or Lincoln, cities governed by their own municipal officers, guarded by massive walls, and linked together by a network of magnificent roads, which extended from one end of the island to the other. Commerce sprang up in ports like that of London; agriculture flourished till Britain became one of the great corn-exporting countries of the world; its mineral resources were explored in the tin mines of Cornwall, the lead mines of Somerset, the iron mines of Northumberland and the Forest of Dean. The wealth of the island grew fast during centuries of unbroken peace, but the evils which were slowly sapping the strength of the Roman Empire at large must have told heavily on the real wealth of the province of Britain. Here, as in Italy or Gaul, the population probably declined as the estates of the landed proprietors grew larger, and the cultivators sank into serfs whose cabins clustered round the luxurious villas of their lords. The mines, if worked by forced labour, must have been a source of endless oppression. Town and country alike were crushed by heavy taxation, while industry was checked by a system of trade guilds which confined each occupation to an hereditary caste. Above all, the purely despotic system of the Roman Government, by crushing all local independence, crushed all local vigour. Men forgot how to fight for their country when they forgot how to govern it.
Such causes of decay were common to every province of the Empire; but there were others that sprang from the peculiar circumstances of Britain itself. The island was weakened by a disunion within, which arose from the partial character of its civilization. It was only in the towns that the conquered Britons became entirely Romanized. The tribes of the rural districts seem to have remained apart, speaking their own tongue and owning some traditional allegiance to their native chiefs. The use of the Roman language may be taken as marking the progress of Roman civilization, and though Latin had wholly superseded the language of the conquered peoples in Spain or Gaul, its use seems to have been confined in Britain to the inhabitants of the towns. It was this disunion that was revealed by the peculiar nature of the danger which threatened Britain from the North. The Picts were simply Britons who had been sheltered from Roman conquest by the fastnesses of the Highlands, and who were at last roused in their turn to attack by the weakness of the province and the hope of plunder. Their invasions penetrated to the heart of the island. Raids so extensive could hardly have been effected without help from within, and the dim history of the time allows us to see not merely an increase of disunion between the Romanized and un-Romanized population of Britain, but even an alliance between the last and their free kinsfolk, the Picts. The struggles of Britain, however, lingered on till dangers nearer home forced the Empire to recall its legions and leave the province to itself. Ever since the birth of Christ the countries which lay round the Mediterranean Sea, and which then comprehended the whole of the civilized world, had rested in peace beneath the rule of Rome. During four hundred years its frontier had held at bay the barbarian world without - the Parthian of the Euphrates, the Numidian of the African desert, the German of the Danube or the Rhine. It was this mass of savage barbarism that at last broke in on the Empire at a time when its force was sapped by internal decay. In the Western dominions of Rome the triumph of the invaders was complete. The Franks conquered and colonized Gaul, the West-Goths conquered and colonized Spain, the Vandals founded a kingdom in Africa, the Burgundians encamped in the border-land between Italy and the Rhone, the East-Goths ruled at last in Italy itself.
It was to defend Italy against the Goths that Rome in 411 recalled her legions from Britain, and though she purposed to send them back again when the danger was over, the moment for their return never came. The province thus left unaided, seems to have fought bravely against its assailants, and once at least to have driven back the Picts to their mountains in a rising of despair. But the threat of fresh inroads found Britain torn with civil quarrels which made a united resistance impossible, while its Pictish enemies strengthened themselves by a league with marauders from Ireland (Scots as they were then called), whose pirate-boats were harrying the western coast of the island, and with a yet more formidable race of pirates who had long been pillaging along the British Channel. These were the English. We do not know whether it was the pressure of other tribes or the example of their German brethren who were now moving in a general attack on the Empire from their forest homes, or simply the barrenness of their coast, which drove the hunters, farmers, fishermen, of the three English tribes to sea. But the daring spirit of their race already broke out in the secrecy and suddenness of their swoop, in the fierceness of their onset, in the careless glee with which they seized either sword or oar. "Foes are they," sang a Roman poet of the time, "fierce beyond other foes, and cunning as they are fierce: the sea is their school of war, and the storm their friend; they are sea-wolves that live on the pillage of the world." To meet the league of Pict, Scot, and Englishman by the forces of the province itself became impossible; and the one course left was to imitate the fatal policy by which the Empire had invited its own doom while striving to avert it, the policy of matching barbarian against barbarian. The rulers of Britain resolved to break the league by detaching the English from it, and to use their new allies against the Pict. By the usual promises of land and pay, a band of English warriors were drawn for this purpose in 449 from Jutland, with their chiefs, Hengest and Horsa, at their head.
Green JR, 1885, A Short History of the English People, London: Macmillan, pp 5-7.