I would rather you read the books, rather than ask for a summary. However: 1) Gildas was not merely "in a bad mood" about his contemporaries. All his most dreadful charges are confirmed by Gregory of Tours' independent evidence of British princes' behaviour in Brittany, and some specific charges by the decrees of the Council of Tours (567 AD) 2) Gildas did not foresee Saxon invasion, but he was quite clear that if there was no moral renewal in society, something dreadful WOULD happen. He thought this would be a Byzantine invasion, and in fact I give evidence that Justinian I had been thinking of using Ostrogoth armies to invade Britain. Considering the war-fighting methods of Justinian and his generals Belisarius and Narses, a Byzantine invasion would certainly have been an apocalyptic event. 3) However, when the British system of kings and kinglets started collapsing just about at the time Gildas died, his warnings were taken to have been prophetic in that specific sense. Both Bede and Wolfstan describe him as a prophet - Wulfstan as a thiodhvita, a seer of the people/nation. 4) However, the relationship between Gildas' warnings and the eventual catastrophe is less than casual. The disastrous in-fighting and incapacity to sustain any kind of permanent order which he denounced, and which contemporary Gaulish evidence confirms, did in fact lead to the sudden and unstoppable English break-out from the "reservations" of east Anglia and possibly Kent to which they had been confined since Badon. In other words, the Britons would have done themselves a world of good if they had listened to their thiodhvita.
Re: Rhemus de excidio
1) Gildas was not merely "in a bad mood" about his contemporaries. All his most dreadful charges are confirmed by Gregory of Tours' independent evidence of British princes' behaviour in Brittany, and some specific charges by the decrees of the Council of Tours (567 AD)
2) Gildas did not foresee Saxon invasion, but he was quite clear that if there was no moral renewal in society, something dreadful WOULD happen. He thought this would be a Byzantine invasion, and in fact I give evidence that Justinian I had been thinking of using Ostrogoth armies to invade Britain. Considering the war-fighting methods of Justinian and his generals Belisarius and Narses, a Byzantine invasion would certainly have been an apocalyptic event.
3) However, when the British system of kings and kinglets started collapsing just about at the time Gildas died, his warnings were taken to have been prophetic in that specific sense. Both Bede and Wolfstan describe him as a prophet - Wulfstan as a thiodhvita, a seer of the people/nation.
4) However, the relationship between Gildas' warnings and the eventual catastrophe is less than casual. The disastrous in-fighting and incapacity to sustain any kind of permanent order which he denounced, and which contemporary Gaulish evidence confirms, did in fact lead to the sudden and unstoppable English break-out from the "reservations" of east Anglia and possibly Kent to which they had been confined since Badon. In other words, the Britons would have done themselves a world of good if they had listened to their thiodhvita.