The manuscript BL Cotton Tiberius A. iii states:
“Then succeeded Alfred, their brother, to the government. And then had elapsed of his age three and twenty winters, and three hundred and ninety-six winters from the time when his kindred first gained the land of Wessex from the Welsh.”
396 years prior to the start of Alfred’s reign, in the year 871, suggests an Adventus Saxonum in the year 475. This, of course, was not the first arrival of Germanic peoples to Britain. However, there was an influx of Saxon invaders around this time as indicated by the chronicle entry for the year 477:
“This year Ælla, and his three sons, Cymen, and Wlencing, and Cissa, came to the land of Britain with three ships, at a place which is named Cymenesora, …”
It would thus seem that the West Saxons and the South Saxons arrived at around the same time. They also appear to have landed in areas that are in close proximity, namely Cerdicesora (Southampton area) and Cymenesora (Selsey area) and then went on to expand their kingdoms westwards and eastwards respectively. Alternatively, it may be that there was no seperate South Saxon invasion and that the 477 entry refers to the West Saxon invasion. A discrepancy of two years in the Chronicles is nothing unusual. An explanation of this idea will be given in a later article entitled “The emergence of Wessex”.
I suggest that when Bede wrote:
“From that day, sometimes the natives, and sometimes their enemies, prevailed, till the year of the siege of Badon hill, when they made no small slaughter of those invaders, about forty-four years after their arrival in Britain.”
his source for this information, the DEB, was referring to this later Adventus, not the one traditionally dated to the year 449. Bede’s version of the DEB is likely to have been closer to Gildas’s original text than any of our later surviving copies. Gildas was a little more precise than Bede with regards to the time interval between the Adventus and Badon when he stated:
“And this commences, a fact I know, as the forty-fourth year, with one month now elapsed; it is also the year of my birth.”
The first year being 475 implies the forty-fourth year is 518, the traditional date for Badon. The battle occurred one month into that year. He states that year is when he was born. The AC tells us that Gildas died in the year 572, giving a plausible life-span of 54 years.
Gildas may have started formulating his ideas concerning the DEB around the age of 20, that is c. 538. Camlan occurred in 539 and could well have been as a result of an internecine feud amongst the Britons, since triad 84 tells us it was one of the Futile Battles of the Island of Britain. Indeed, it may have been one of the triggers that set Gildas on the path to writing the DEB 10 years later, around the year 548.
The Chronicon Britannicum derived Gildas’s birthdate incorrectly by adding 43 years to the Adventus Anglorum:
CCCCXLVII. Angli in majorem Britanniam venerunt, & Britones inde ejecerunt
CCCCXC. Natus est S. Gildas. Hiis diebus fuit Arturus fortis.
 Adapted from Ingram, J., 1823, 20.
 Adapted from Giles, J.A., 1914, 8.
 Adapted from Giles, J.A., 1859, 26.
 Adapted from Williams, H., 1899, 63.
 Bromwich, R., 2006, 217.