The seat of war then appears to shift southward. Gwinnion may have been fought to drive off some of the invaders who had got into the rear of the Britons while the latter were fighting at the Forth. Urbs Legionis is probably in this instance York. The Ribruit and Agned cannot be identified; Mons Badonis or Badonicus is supposed to have been Bath, but there is no reason for this identification; it probably arose out of the similarity between Badon and the English appellation of Aquae Sulis. Wadon Hill, near Avebury, and Badbury (? Baden-burh) Rings in Dorset have both been identified with this mysterious site. It seems from Gildas that it was a fortress. Probably it was besieged by the invaders, and relieved by Arthur in a battle which stayed the English advance for many years. [Illustration: BRITAIN FROM ABOUT 500-570. Showing the probable effects of the Romano-British rally under Ambrosius Aurelianus and his successors. No towns are indicated within the English areas, as it is probable that all had been deserted or destroyed.] The date of these events is doubtful. Gildas, in a sentence which is the despair of all Latinists, seems to say that the battle of Mons Badonicus was fought forty-four years and one month before he wrote his book. We know that he wrote some years before the death of King Mælgwn of Gwynedd (A.D. 547). This fixes the date of the battle at about 500. The ‘Annales Cambriæ’ put it in 516, but the ‘Annales’ are as late as the ‘Anglo-Saxon Chronicle.’ Mr. E. B. Nicholson has suggested that the forty-four years are to be reckoned from the appearance of Ambrosius to 516. It is quite possible that the great leader did commence his campaigns about 472, but Gildas hardly gives us the impression of a man capable of very accurate chronology. But if he were born on the day of the battle, as he says, it would be a simple matter. On the whole, we may reasonably say that the battle was fought about the year 500, and its effect was to stay the advance of the English in the south for at least forty-four years. One would willingly hear more of the men whose efforts for a while stayed the flowing English tide; but practically all that is known is here set down. The ‘Annales Cambriæ’ state that twenty-one years after Mons Badonicus Arthur and Medrant fell in a battle at Camlan. Arthur is repeatedly mentioned in the bardic poems of Wales, but we cannot tell to what extent these works may have been altered in later ages.