DOC 4 -- Nennius, History of the Britons
Nennius was an English historian writing in the 8th century. He is a major source for the legend of King Arthur. While he wasn't the most carfeul historian, his writing cannot be dismissed as complete invention. There probably was a King Arthur at this time, but much of the other information provided below is questionable.
Chapter 56
At that time [the late 5th century], the Saxons grew strong by virtue of their large number and increased in power in Britain. Hengist having died, however, his son Octha crossed from the northern part of Britain to the kingdom of Kent and from him are descended the kings of Kent. Then Arthur along with the kings of Britain fought against them in those days, but Arthur himself was the military commander ["dux bellorum"]. His first battle was at the mouth of the river which is called Glein. His second, third, fourth, and fifth battles were above another river which is called Dubglas and is in the region of Linnuis.
The sixth battle was above the river which
is called Bassas. The seventh battle was in the forest of Celidon, that
is Cat Coit Celidon. The eighth battle was at the fortress of Guinnion,
in which Arthur carried the image of holy Mary ever virgin on his shoulders;
and the pagans were put to flight on that day. And through the power of
our Lord Jesus Christ and through the power of the blessed Virgin Mary
his mother there was great slaughter among them. The ninth battle was waged
in the City of the Legion. The tenth battle was waged on the banks of a
river which is called Tribruit. The eleventh battle was fought on the mountain
which is called Agnet. The twelfth battle was on Mount Badon in which there
fell in one day 960 men from one charge by Arthur; and no one struck them
down except Arthur himself, and in all the wars he emerged as victor. And
while they were being defeated in all the battles, they were seeking assistance
from Germany and their numbers were being augmented many times over without
interruption. And they brought over kings from Germany that they might
reign over them in Britain, right down to the time in which Ida reigned,
who was son of Eobba. He was the first king in Bernicia, i.e., in Berneich.
Chapter 73
There is another marvel in the region which
is called Buelt. There is a mound of stones there and one stone placed
above
the pile with the pawprint of a dog in it. When Cabal, who was the dog
of Arthur the soldier, was hunting the boar Troynt, he impressed his print
in the stone, and afterwards Arthur assembled a stone mound under the stone
with the print of his dog, and it is called the Carn Cabal. And men come
and remove the stone in their hands for the length of a day and a night;
and on the next day it is found on top of its mound.
There is another wonder in the region which is called Ercing. A tomb is located there next to a spring which is called Licat Amr; and the name of the man who is buried in the tomb was called thus: Amr. He was the son of Arthur the soldier, and Arthur himself killed and buried him in that very place. And men come to measure the grave and find it sometimes six feet in length, sometimes nine, sometimes twelve, sometimes fifteen. At whatever length you might measure it at one time, a second time you will not find it to have the same length--and I myself have put this to the test.
[Source: http://www.fordham.edu/halsall/ancient/asbook.html]