Gildas Bandonicus, a British [i.e. Keltic] monk, lived in the 6th century. In the 540s - in the most aggressive language - he set out to denounce the wickedness of his times.

Chapter 23.

• Then all the councillors, together with that proud tyrant Gurthrigern [Vortigern], the British king, were so blinded, that, as a protection to their country [from the Picts], they sealed its doom by inviting in among them (like wolves into the sheep-fold), the fierce and impious Saxons, a race hateful both to God and men, to repel the invasions of the northern nations.
• for it was foretold by a certain soothsayer among them, that they [Saxons] should occupy the country to which they were sailing three hundred years, and half of that time, a hundred and fifty years, should plunder and despoil the same.
• Their mother-land, finding her first brood thus successful, sends forth a larger company of her wolfish offspring, which sailing over, join themselves to their bastard-born comrades.
• The barbarians being thus introduced as soldiers into the island, to encounter, as they falsely said, any dangers in defence of their hospitable entertainers, obtain an allowance of provisions, which, for some time being plentifully bestowed, stopped their doggish mouths. Yet they complain that their monthly supplies are not furnished in sufficient abundance, and they industriously aggravate each occasion of quarrel, saying that unless more liberality is shown them, they will break the treaty and plunder the whole island. In a short time, they follow up their threats with deeds.

Chapter 24.

• then ... destroying the neighbouring towns and lands, it [the Saxon horde] reached the other side of the island, and dipped its red and savage tongue in the western ocean. In these assaults, therefore, not unlike that of the Assyrian upon Judea,
• So that all the columns were levelled with the ground by the frequent strokes of the battering-ram, all the husbandmen routed, together with their bishops, priests, and people, whilst the sword gleamed, and the flames crackled around them on every side. Lamentable to behold, in the midst of the streets lay the tops of lofty towers, tumbled to the ground, stones of high walls, holy altars, fragments of human bodies, covered with livid clots of coagulated blood,

Chapter 25.

• Some [of the Romanized Britons], therefore, of the miserable remnant, being taken in the mountains, were murdered in great numbers; others, constrained by famine, came and yielded themselves to be slaves for ever to their foes, Others, committing the safeguard of their lives, which were in continual jeopardy, to the mountains, precipices, thickly wooded forests, and to the rocks of the seas (albeit with trembling hearts), remained still in their country.
• [others] that they might not be brought to utter destruction, took arms under the conduct of Ambrosius Aurelianus, a modest man, who of all the Roman nation was then alone in the confusion of this troubled period by chance left alive.