Arthur according to
Geoffrey of Monmouth
Monmouth is the one who brings us Uther Pendragon, just like that, out of the blue.
Who is this Uther and did he exist only in Monmouth's imagination? According to "The history of the Kings of Britain" Uther begot his name from the Comet and the two Golden Dragons which he made because of Merlin's prophecy that the next king would be 'a dragon's head'. Monmouth has called his Utherpendragon (Ythr ben dragwn) from day one. According to Monmouth Uther is the third son of Constantine (the last Roman emperor in Britain) and brother to Aurelius Ambrosius. The other brother was called Constans and was a monk who was persuaded to accept the throne. He did accept this, but put Vortigern in charge.
When Uther came of age, he fought Vortigern and took back the power belonging to his bloodline. Either from Constans as well from Uther there are no official records. We have to assume that Monmouth's imagination was at work here. Again it is Monmouth who 'invents' Merlin and herewith a great deal of the Arthurian Legend. As I state in my 'merlin'-page: without Merlin no Arthur, no Excalibur, no Legend.
Basicly Monmouth is the 'father of the legend', for he comes along with both Uther and Merlin. Tells us the story of the sword in the stone, of the kingmaking, and of the battle between Arthur and Mordred. Only a few centuries later Lancelot and Guenevere are introduced by French writers as well as the Round Table and the Quest for the Holy Grail. Monmouth tells us the story of the Duke of Cornwell and his wife Ygerna (Igraine) and the rest is, as you might say, 'history'.
Now where did Monmouth find his material?
There are two possible origins: his big thumb (also knwon as: imagination) and a little book he got from Walter the Archdeacon (a.k.a. Walter of Oxford) which was supposed to be 'a certain very ancient book written in the British language', however this book has never been recovered. Or, as Sir John Lloyd wrote: "No Welsh composition exists which can be reasonable looked upon as teh original, or even the groundwork, of the History of the Kings of Britain". Of course, this does not mean the book never did exist. For all we know this book was an early copy of the Mabinogion in which tellings of Taliesin (who possibly stood for Merlin), Saint David, Urien of Rheged and of course Culhwch and Olwen. Or perhaps the book was named a book, but it really was a number of ancient stories which Walter the Archdeacon told Monmouth, who wrote them down later.
Whatever the truth may be: I think it is clear that Geoffrey of Monmouth made up a lot of his stories in "The history of the Kings of Britain" or 'borrowed' them from someone else.
And so Monmouth became the Father of the Legend.