Excerpts from Geoffrey of Monmouth's Historia Regum Brittaniae
CHAP. III. -- Arthur makes the Saxons his tributaries.
. . . From thence they pursued their furious march to the town of Bath, and laid siege to it. When the king had intelligence of it, he was beyond measure surprised at their proceedings, and immediately gave orders for the execution of the hostages. And desisting from an attempt which he had entered upon to reduce the Scots and Picts, he marched with the utmost expedition to raise the siege; but laboured under very great difficulties, because he had left his nephew Hoel sick at Alclud. At length, having entered the province of Somerset, and beheld how the siege was carried on, he addressed himself to his followers in these words: "Since these impious and detestable Saxons have disdained to keep faith with me, I, to keep faith with God, will endeavour to revenge the blood of my countrymen this day upon them. To arms, soldiers, to arms, and courageously fall upon the perfidious wretches, over whom we shall, with Christ assisting us, undoubtedly obtain the victory."
CHAP. IV. -- Dubricius's speech against the treacherous Saxons. Arthur with his own hand kills four hundred and seventy Saxons in one battle. Colgrin and Baldulph are killed in the same.
When he had done speaking, St. Dubricius, archbishop of Legions, going to the top of a hill, cried out with a loud voice, "You that have the honour to profess the Christian faith, keep fixed in your minds the love which you owe to your country and fellow subjects, whose sufferings by the treachery of the pagans will be an everlasting reproach to you, if you do not courageously defend them. It is your country which you fight for, and for which you should, when required, voluntarily suffer death; for that itself is victory and the curse of the soul. For he that shall die for his brethren, offers himself a living sacrifice to God, and has Christ for his example, who condescended to lay down his life for his brethren. If therefore any of you shall be killed in this war, that death itself, which is suffered in so glorious a cause, shall be to him for penance and absolution of all his sins." At these words, all of them, encouraged with the benediction of the holy prelate, instantly armed themselves, and prepared to obey his orders. Also Arthur himself, having put on a coat of mail suitable to the grandeur of so powerful a king, placed a golden helmet upon his head, on which was engraven the figure of a dragon; and on his shoulders his shield called Priwen; upon which the picture of the blessed Mary, mother of God, was painted, in order to put him frequently in mind of her. Then girding on his Caliburn, which was an excellent sword made in the isle of Avallon, he graced his right hand with his lance, named Ron, which was hard, broad, and fit for slaughter. After this, having placed his men in order, he boldly attacked the Saxons, who were drawn out in the shape of a wedge, as their manner was. And they, notwithstanding that the Britons fought with great eagerness, made a noble defence all that day; but at length, towards sunsetting, climbed up the next mountain, which served them for a camp: for they desired no larger extent of ground, since they confided very much in their numbers. The next morning Arthur, with his army, went up the mountain, but lost many of his men in the ascent, by the advantage which the Saxons had in their station on the top, from whence they could pour down upon him with much greater speed, than he was able to advance against them. Notwithstanding, after a very hard struggle, the Britons gained the summit of the hill, and quickly came to a close engagement with the enemy, who again gave them a warm reception, and made a vigorous defence. In this manner was a great part of that day also spent; whereupon Arthur, provoked to see the little advantage he had yet gained, and that victory still continued in suspense, drew out his Caliburn, and, calling upon the name of the blessed Virgin, rushed forward with great fury into the thickest of the enemy's ranks; of whom (such was the merit of his prayers) not one escaped alive that felt the fury of his sword; neither did he give over the fury of his assault until he had, with his Caliburn alone, killed four hundred and seventy men. The Britons, seeing this, followed their leader in great multitudes, and made slaughter on all sides; so that Colgrin, and Baldulph his brother, and many thousands more, fell before them. But Cheldric, in this imminent danger of his men, betook himself to flight.
CHAP. V. -- The Saxons, after their leader Cheldric was killed, are all compelled by Cador to surrender.
The victory being thus gained, the king commanded Cador, duke of Cornwall, to pursue them, while he himself should hasten his march into Albania: from whence he had advice that the Scots and Picts were besieging Alclud, in which, as we said before, Hoel lay sick. Therefore he hastened to his assistance, for fear he might fall into the hands of the barbarians. In the meantime the duke of Cornwall, who had the command of ten thousand men, would not as yet pursue the Saxons in their flight, but speedily made himself master of their ships, to hinder their getting on board, and manned them with his best soldiers, who were to beat back the pagans in case they should flee thither: after this he hastily pursued the enemy, according to Arthur's command, and allowed no quarter to those he could overtake. So that they whose behaviour before was so cruel and insolent, now with timorous hearts fled for shelter, sometimes to the coverts of the woods, sometimes to mountains and caves, to prolong a wretched life. At last, when none of these places could afford them a safe retreat, they entered the Isle of Thanet with their broken forces; but neither did they there get free from the duke of Cornwall's pursuit, for he still continued slaughtering them, and gave them no respite till he had killed Cheldric, and taken hostage for the surrender of the rest. (Pages 216 - 218)
See The Battle of Mount Badon page.