General Notes

Vortigern, born Vitalinis, was a Roman Britain who used his influence to have Constantius, the son of Maxentius (Macsen Weidleg) assassinated.  He then assumed the throne of Britain by right of his marriage.  He was unpopular among the Britons, so as a means of protecting his throne, Vortigern invited two bands of Saxon warriors under the leadership of Hengist and Horsa to serve as his elite guard.  The Saxons were considered enemies by the Britons and the general unease caused Vortigern to invite even more Saxons to Britain.  He then became infatuated with the daughter of Hengist and abandoned his wife, Severa, along with their children to marry the Saxon princess.  As a gift to the family of his new bride, Vortigern gave the eastern coast of Britain to the Saxons for their home, beginning the Anglo-Saxon invasion.  War quickly erupted as outraged Britons rose up to reclaim their homeland. The sons of Vortigern had fled to Gaul for safety, where they raised an army and returned to assist the Britons in overthrowing their father and his Saxon merceneries.

VORTIGERN

THE MOST hated man in Britain, as he later became known, was Vortigern Vorteneu. The Welsh form of this is Gwrtheyrn Gwrtheneu (the Thin). Despite the name being synonymous with the man, Vortigern has long been accepted as only a title, with Pictish, or perhaps Northern British overtones. It means "Over-King", and there are some indications that, like his semi-legendary forebears, his real name was Vitalis (Gwidol in Welsh) or Vitalinus (Gwidolin), though his origins are obscure. His name would almost certainly have been Roman in influence, although he was probably aware of its Celtic version. The north and west of Britannia was only ever under Roman military rule, so Celtic traditions were still very strong there. The other possibility, equally strong, put forward by Charles Thomas, is that Bede knew of Vortigern as Vertigernus or Uuertigernus, representing a British name Wortigernos (see the introduction on Gildas for a fuller explanation).
His power-base was always the area along the Welsh border, and while he was High King, his eldest son Vortimer set up a thriving kingdom in Gwent. Vortigern himself appears to have spent more of his time, and exercised more direct control in Caer Gloui (Gloucester) in his early years. His great grandfather is said to have been Gloyw Gwallthir (Long-Hair), one of the city's supposed founders (Gloyw = Glou-, and Latin castrum (fort) = British caer or Saxon cester). This name is still linked to the place itself in its nickname of "Gloucester Long-Wall", but the appendage to Gloyw's name indicates he was a long-haired Pict. This is also born out to an extent in the name Vortigern itself. "gern" was a Pictish (or pre-Pict) word for leader.
Despite this Pictish link, the "Life of St Cadog" gives Vortigern an alternative and very typically Celtic ancestry descending from the Celtic gods, Beli Mawr, Lludd Llaw Ereint & Afallach. Pictish descent was always measured through the female side, so perhaps this explains the apparent conflict. Vortigern could have possessed a Pictish female in his ancestry, a possible wife of Gloyw's, not unlikely if she was from the Southern Picts around Manau Goutoddin or the Clyde.
The St Cadog ancestry shows too few generations to be complete, but it is replicated in the King List for Vortigern's Powys, as similar ancestries are for other kings, such as Gwent, Dyfed, and Gwynedd. The ancestry of Celtic kings was very important to their prestige and their clan name, so even minor kings (who were usually descended from greater royal houses anyway) would find an ancestry that linked them to their royal title.
Vortigern became High King of Britain in around 425, after years of building up his power and position. Its entirely possible that, given the fact that the Romano-Britons at this time were still very much following standard Roman policies on defence and their way of life, that he adjusted the title to become Emperor of Britain. The precedence would have been his own father in law, Magnus Maximus, and the more recent claimant to Rome, Constantine III, who left Britain in 407. There was no possibility of following these two overseas to claim a now much reduced Rome, even if the manpower was available, which it was not. The title of emperor would bear much more meaning to the Romanised Britons who were in command of Britannia, before the mid-century Celtic resurgence took hold.
Between AD 380 - 400 Vortigern married Severa ferch Macsen (daughter of Magnus Maximus, the Roman general proclaimed emperor in Britain in 383, and responsible for large scale changes in the way Britain defended itself before he left to pursue his claim to the purple). Later, he married again.

Vortigern & Vortimer
British Chronology

SOURCE: http://www.britannia.com/history/biographies/vortig.html
Estimates of when Vortigern came to power in Britain vary dramatically: possibly around 425, perhaps about 440-5. He may have been a "high-king." It is thought by some that Vortigern is not a name at all, but a title, meaning "over king." Even his origins are disputed. According to the available sources, Vortigern was a weak man of little character, possessing few redeeming personal qualities. If these sources are correct, it is hard to imagine that his ascent to power was by the acclaimation of the members of Britain's ruling council, and is much easier to believe that he gained his throne by treachery and murder.

Some support for this view is lent by Geoffrey of Monmouth, in his 12th century "History of the Kings of Britain." In it, Geoffrey tells us of a King Constantine, who had three sons, Constans, Aurelius Ambrosius (the Ambrosius Aurelianus of actual history) and Uther Pendragon (the legendary future father of Arthur). Geoffrey says that Constantine was killed by a Pictish assassin, leaving the eldest son, Constans, as king.

Vortigern appears to have climbed his way high up the greasy pole by securing an inspired marriage to Severa, the daughter of the Constantine's predecessor and national hero, Magnus Maximus. As Constans was still quite young, Vortigern was able to have himself installed as the king's advisor, and before long, conspired to have the young king killed. With the king out of the way, Vortigern seized the crown for himself, realizing that Aurelius Ambrosius and Uther Pendragon were mere babes and weren't in a position, at that time, to frustrate his designs. Luckily for the young brothers, they were bundled up and escaped to the court of their cousin, Budic I, in Brittany.

According to the "Historia Brittonum," a ninth century compilation of writings by a Welsh monk called Nennius, Vortigern came to power threatened with three dangers on his mind:

"Vortigern ruled in Britain and during his rule in Britain he was under pressure, from fear of the Picts and the Irish (Scots), and of a Roman invasion, and, not least, from dread of Ambrosius."

The fear of the Picts and Scots was completely natural since the British northern defenses were ineffective and in severe disarray. The fear of a Roman invasion suggests either great paranoia on Vortigern's part (the Romans had had no presence in Britain for years) or that there was very good reason (of which we are ignorant, today) to be concerned about a reappearance of Roman soldiers on the shores of Britain. The final fear, of Ambrosius, was to have fatal consequences. Vortigern dreaded retribution, for the murder of his father and older brother, but Ambrosius was still young and the High-King could afford to defer any action for some years.

[5th Century Caer-Guricon (Wroxeter in Shropshire)]

It was during Vortigern's reign that St. Germanus appears at the Royal Court. Traditional this is said to have been St. Germanus of Auxerre, who is known to have visited Britain at this time to stamp out the Palagian heresy that had become so popular. His first journey took him from Caer-Rebuti (Richborough) to Caer-Lundein (London) and Caer-Mincip (St.Albans), all in South-East England. However, stories of his leading an army against invading Saxon pirates, probably in Cheshire, may refer to a different man. The saint who spent some time in Vortigern's presence - probably at Caer-Guricon (Wroxeter, Shropshire) where excavation has revealed the residence of a powerful 5th century noble - may have been the Breton St. Garmon who was active across Wales. This saint accused Vortigern of fathering a child by his own daughter. Though disgusted by the British High-King, Garmon - or Germanus - favoured the man's sons, at least two of whom he appears to have blessed.

Even with the support of his brothers-in-law, who were now powerful rulers in Wales, Vortigern's grip on the country was still shaky; but when Severa died the situation worsened. To aid the Britons in their defense against the increasingly brutal raids from the northern tribes, Vortigern therefore authorized the use of Saxon and Jutish mercenaries, led by Princes Hengist & Horsa. In line with the standard Roman practice of employing one barbarian tribe to defend against another, the Saxons received land to be used for settlement in exchange for their services.

Geoffrey of Monmouth claims that the two brothers asked for all the land they could cover with a single ox-hide. Vortigern eagerly agreed, but found that Hengist cut the hide into a lengthy thong that was able to encompass the whole city of Caer-Correi (Caistor, Lincs)! Vortigern must, however, have found reassurance in the words of the Jutish chief, as recorded in the "Kentish Chronicle":

"Hengest said to Vortigern. . .'Take my advice, and you will never fear conquest by any man or any people, for my people are strong. I will invite my son and his cousin to fight against the Irish, for they are fine warriors.'"

The anti-Pict/Irish strategy that Vortigern chose to employ proved to be successful, since these tribes were never a problem, again, and the arrangement between the Saxons under their leader, Hengest, and Vortigern was agreeable to both parties for some time. Later, however, they tricked the High-King again: this time into handing over to them the Sub-Kingdom of Ceint (Kent). Getting drunk at a celebratory feast, the foolish Vortigern fell deeply in love with Hengist's daughter, Rowena. He promised Hengist anything he wanted, if only he could marry her. Ceint was the Saxon's price.

Sickened by the betrayal of his countrymen, Vortigern's eldest son, Vortimer, declared himself a rival British leader, raised an army and, for a short time, managed to stem the Saxon advance. Wounded in battle, however, he was poisoned by his step-mother. From their secure power-base, the Saxons then demanded more food and clothing to supply their increased numbers and Vortigern refused them, saying, "we cannot give you more food and clothing for your numbers are grown." The Saxons, however, would not accept this answer. Nennius tells us,

"So they took counsel with their elders to break the peace."

They tore through the land, leaving devastation wherever they went. Many were killed during the ensuing battles, amongst them, Horsa & Vortigern's son, Catigern. Hengist eventually called for a peace conference on Salisbury Plain. The British arrived and were promptly cut down where they stood. This decision on the part of the Saxons would result in several generations of war with the Britons.

[Fighting Dragons at Dinas Emrys] Vortigern escaped to set up a stronghold in the west. He chose to build a castle on the southern slopes of Yr Aran, above Beddgelert (Gwynedd). Construction began. However, every morning the previous day's work was found demolished. Vortigern's magicians told him to seek a boy with no father, born of the fairies. He would be able to solve the High-King's problem. Vortigern's men searched far and wide and discovered such a boy at what was soon to become Caer-Fyrddin (Carmarthen). His name was Myrddin Emrys, or "Merlin" for short. Merlin revealed that at night the mountain shook so that all buildings collapsed, because beneath it were buried two fighting dragons. One white representing the Saxons and one red representing the British, and the white one was winning! Afraid of such an omen, Vortigern fled.

Disillusioned, the British finally rebelled against their High-King. Ambrosius Aurelianus (Emrys Wledig), of whom Vortigern had previously had no fear, had by now grown into a burly young man and took his place in the events of the time to lead their struggle. Merlin handed over to him the mountain site where Vortigern had failed to build, and it became his fort of Dinas Emrys. Vortigern took refuge in the refortified hillfort of Tre'r Ceiri in Yr Eifl (the Rivals) in Lleyn, but Ambrosius pursued him and drove him south, via Nant Gwetheyrn and the sea to Ergyng and a wooden castle on the old hillfort of Caer-Guorthigirn (Little Doward) above Ganarew. Here, the castle was miraculously struck by lightning and Vortigern burnt to death! He was later buried in a small chapel in Nant Gwrtheyrn (Lleyn).

Thus, it was left to Ambrosius Aurelianus to halt the Saxon advance.