GILDAS is remembered as the author of ‘De Excidio Britanniae’ (On the Ruin of Britain). The Anglo-Saxon historian Bede, who made use of ‘De Excidio’ in his ‘Historia Ecclesiastica’, calls him the Britons' “own historian” (H.E. Book I Chapter 22), but it was not Gildas' purpose to write a work of history.
“Whatever my attempt shall be in this epistle, made more in tears than in denunciation, in poor style, I allow, but with good intent, let no man regard me as if about to speak under the influence of contempt for men in general, or with an idea of superiority to all, because I weep the general decay of good, and the heaping up of evils, with tearful complaint. On the contrary, let him think of me as a man that will speak out of a feeling of condolence with my country's losses and its miseries, and sharing in the joy of remedies. It is not so much my purpose to narrate the dangers of savage warfare incurred by brave soldiers, as to tell of the dangers caused by indolent men.”
‘De Excidio Britanniae’ Chapter 1
‘De Excidio’ is essentially a long sermon concerned with the evils which the Britons have brought on themselves by their sinful behaviour. Gildas addresses himself to five British rulers, one of whom is Maglocunus. Maglocunus is identified with Maelgwn, king of Gwynedd, whose death is dated (though with little degree of reliability), by the ‘Annales Cambriae’, to 547. Since Gildas must have been addressing Maelgwn prior to this, a date in the region of 545 is often proposed for the composition of ‘De Excidio’. However, the water is clouded by a remark Gildas makes – in the surviving text its meaning is obscure – concerning “the siege of Badon Hill” (where the Britons defeated the Anglo-Saxons), “the forty-fourth year, with one month now elapsed” and his own birth (Chapter 26). By and large, the interpretation placed on Gildas' comment is that he was writing in the forty-fourth year after Badon, in which same year he had been born. The ‘Annales Cambriae’ also provide a date for Badon: 516. Simple arithmetic would then date ‘De Excidio’ to 559/60, i.e. after Maelgwn's death. It seems, though, as if Bede, whose own copy of ‘De Excidio’ must have been earlier than any surviving copy (the earliest is 10th century), interpreted Gildas as meaning that the Anglo-Saxon defeat at Badon occurred “about forty-four years after their arrival in Britain” (H.E. Book I Chapter 16). Using this interpretation there is no conflict, but Bede doesn't directly state that his “about forty-four years” is based on Gildas' comment – it could simply be coincidence. At any rate, the debate about just when Gildas was writing continues, as, indeed, does the debate about just where he wrote – the most popular suggestion seems to be somewhere in south-western Britain.
Gildas ‘De Excidio Britanniae’ by Hugh Williams
Bede ‘Historia Ecclesiastica Gentis Anglorum’ by A.M. Sellar
In fact, the oldest surviving manuscript (British Library MS Cotton Vitellius A vi) was badly damaged by fire in 1731. Fortunately, the text had previously been printed.