After the death of Mempricius, his son Ebraucus, who was very tall and a man of remarkable strength, took over the government of Britain and held it for thirty-nine years. He was the first after Brutus to sail a fleet to the shores of Gaul. He made war upon the provinces of the Gauls, slaughtering their menfolk and sacking their cities. By the time he came back victorious he was enriched with a vast booty of gold and silver. At a later date he founded a city on the farther side of the Humber, which city he called Kaerebrauc after himself, that is to say the City of Ebraucus. At that time King David was reigning in Judea and Silvius Latinus was King in Italy. In Israel, Gad, Nathan and Asaph were the prophets. [II.7]

Geoffrey writes that YORK was founded by Ebraucus, son of Mempricius. It seems he has built the name on the Latin name for the city, Eboracum. York was a prominent Roman settlement: the York Archaeological Trust maintains an interesting Roman York site.

While Tatlock observes that there is nothing in Geoffrey's frequent references to York to suggest local knowledge (p. 22), it is clear that the city looms large throughout the Historia. It is a centre of government, where kings are crowned, govern, and are buried:

As soon as he had won this victory Belinus summoned all his leaders to York, for he wanted to discuss with them what he should do with the King of the Danes. [III.4]

When this oath had been ratified, Elidurus led Archgallo to York and there he took the crown from his own head and placed it on that of his brother. [III.17]

Six years passed and then Cassivelaunus died and was buried in York. [IV.11]

Eleven years passed and then Constantius himself died at York and bequeathed his kingdom to his son. [V.6]

Brian landed at Southampton.... he set out for York, where Edwin was living at that time. [XII.7]

The city is also a centre of religion, perhaps reflecting the prominence of the see in Geoffrey's day:

At that time there were twenty-eight flamens in Britain and three archflamens, to whose jurisdiction the other spiritual leaders and judges of public morals were subject. At the Pope's bidding, the missionaries converted these men from their idolatry. Where there were flamens they placed bishops and where there were archflamens they appointed archbishops. The seats of the archflamens had been in three noble cities, London, York and the City of the Legions, the site of which last, by the River Usk in Glamorgan, is still shown by its ancient walls and buildings.... Parishes were appointed off, Deira being placed under the Metropolitan of York, along with Albany, for the great River Humber divides these two from Loegria. [IV.19]

With his enemies beaten, Aurelius summoned to York his leading men and the princes of his realm, and ordered the to restore the churches which the Saxon people had destroyed. He himself began to rebuild the metropolitan cathedral of that city and the other episcopal churches in the see. [VIII.9]

The two metropolitan sees of York and the City of the Legions were without incumbents. With the general consent of his people, whom he wished to consult in this matter, Aurelius gave York to Samson, a most distinguished man who was famous for his great piety. [VIII.12]

Once he had pardoned the Scottish people, the King moved to York, where he proposed to celebrate the coming feast of the Nativity of our Lord. As he rode into the city, Arthur grieved to see the desolate state of the holy churches. Samson, the saintly Archbishop, had been driven out, and with him all men of the Christian faith. The half-burnt churches no longer celebrated God's holy office. The fury of the pagans had been so great that it had brought everything to an end. Arthur therefore summoned the clergy and the people, and appointed his own chaplain, Piramus, as Metropolitan of that see. He rebuilt the churches, which had been razed to the ground, and he graced them with religious communities of men and women. He restored to their family honours the nobles who had been driven out by the Saxons invasions. There were in York three brothers sprung from the royal line, Loth, Urian and Auguselus, who had been Princes in those parts before the Saxon victories. Arthur was determined to do for them what he had done for the others: that is, to grant them back their hereditary rights. [IX.8-9]

When the two archbishops, Theonus of London and Tadioceus of York, saw that all the churches under their jurisdiction were razed to the ground, they fled with such priests as remained alive after such a calamity to the shelter of the forests of Wales. They took with them the relics of the saints, for they were afraid that all these holy bones of men of ancient times would be destroyed by the barbarian invasion, if they allowed themselves to be martyred where they stood... [XI.10]

The frequent references to the restoration of the churches of York may reflect the reality of such buildings as the great cathedral. While the current York Minster dates to the 13th century, its foundations show just how many buildings had previously occupied the site. Fountains Abbey, north of the city, was founded in Geoffrey's lifetime, but again, it achieved its greatest prominence later, in the 13th century.

Because of York's religious and governmental significance in the Historia, battles often occur at the city:

When Sulgenius was no longer able to resist Severus, he crossed the sea to Scythia, hoping to be restored to power with the help of the Picts. He collected together all the young men of that country, returned to Britain with a huge fleet and besieged York. As soon as this was known among the various tribes, the greater part of the Britons deserted Severus and joined Sulgenius. Severus did not let this deter him from his undertaking. He assembled his Romans and those Britons who were still faithful to him, marched off to the siege and fought with Sulgenius. Just at the moment when the battle which he had brought about was reaching its height, Severus was killed, with many of his men, and Sulgenius was mortally wounded. Severus was later buried in York, which his legions had occupied. [V.2]

Vortigern immediately conceded everything they demanded, given only that he might be allowed to escape alive. When everything had been promised them on oath, the Saxons freed him from his chains. They went first to London and captured the city. Next they took York, Lincoln and Winchester, ravaging the neighbouring countryside and attacking the peasantry, just as wolves attack sheep which the shepherds have forsaken. [VI.16]

The pagans turned in flight, each man for himself. Some fled to the towns, some to the thickly-wooded mountains, and others again to their own ships. Hengest's son Octa retreated to York with the biggest band; and his kinsman Eosa garrisoned that town with a great force of armed men.... Then Aurelius led his army to York in order to besiege Octa, the son of Hengest. When Aurelius started investing the city, Octa had doubts as to whether or not he should resist and defend it against such a huge army. He took the advice of his men and then emerged with the more noble of those who were with him, carrying a chain in his hand and having coarse gravel on his head... [VIII.7-8]

Octa put himself in the centre of this huge army and invaded the northern provinces. He went on satiating his lust for cruelty until he had destroyed all the towns and strong-points from Albany as far as York. Finally, just as he had begun to besiege that town, Utherpendragon arrived with the entire strength of his kingdom and met Octa in a pitched battle. The Saxons resisted manfully. They remained unbroken in the face of the assaults by the Britons and in the end they drove their enemy back in flight. [VIII.18]

Colgrin fled, and Arthur pursued him; then Colgrin entered York and Arthur besieged him there. As soon as Badulf, the brother of Colgrin, heard of the latter's flight, he came to the siege with six thousand troops, in the hope of freeing the beleaguered man. At the time when his brother had gone into battle, Baldulf himself had been on the sea-coast, where he was awaiting the arrival of Duke Cheldric, who was on his way from Germany to bring them support. When he was some ten miles distant from the city of York, Baldulf decided to take the advantage of a night march, so that he could launch an unexpected attack. Arthur heard of this and ordered Cador, Duke of Cornwall, to march to meet Baldulf that same night, with six hundred cavalry and three thousand foot. Cador surrounded the road along which the enemy was marching and attacked the Saxons unexpectedly.... Once Baldulf had come to the conclusion that no other means of access was open to him, he cut short his hair and his beard and dressed himself up as a minstrel with a harp. He strode up and down in the camp, pretending to be a harpist by playing melodies on his instrument. No one suspected him and he moved nearer and nearer to the city walls, keeping up the same pretence all the time. In the end he was observed by the besieged, dragged up over the top of the walls on ropes and taken to his brother.... Finally, when, after exhaustive discussions, they had abandoned all hope of ever escaping, messengers returned from Germany to say that they had brought with them to Albany six hundred ships which were commanded by Cheldric and loaded with brave soldiery. When Arthur's advisers learned this, they dissuaded him from continuing the siege any longer.... [IX.1]

... the Perjurer [Mordred] reformed his army and so marched into Winchester on the following night. When this was announced to Queen Guinevere, she gave way to despair. She fled from York to the City of the Legions and there, in the church of Julius the Martyr, she took her vows among the nuns, promising to lead a chaste life. [XI.2]

It is understandable that York should be a frequent location for battles and sieges: York's walls date back to Roman times, and would doubtless have been impressive in Geoffrey's day. There is a fair bit of information about the history of the city walls on the York city site. In Geoffrey's day, the most prominent medieval fortification would presumably have been Clifford's Tower, built by William the Conqueror.

York also appears twice in Merlin's prophecies:

Religion shall be destroyed a second time and the sees of the primates will be moved to other places. London's high dignity shall adorn Durobernia: and the seventh pastor of York will be visited in the realm of Armorica. [VII.3]

The Charioteer of York will soothe the people. He will throw his master out and climb up into the chariot which he is driving. He will draw his sword and threaten the East, and he will fill with blood the ruts made by his wheels. Next he will tur himself into a Seafish and mate with a Snake which has attracted him by its hissing. [VII.4]