The eighth battle was near the fort Guinnion, where Arthur bore the image of the Holy Virgin, mother of God, upon his shoulders, and through the power of our Lord Jesus Christ, and the holy Mary, put the Saxons to flight, and pursued them whole day with great slaughter.
When the winter broke, Aulus Hectorius rode south with his army, where he was met at the old Roman fort at Vinovium by Osgar Ravenshield, an emissary of the Bretwalda. He announced that the heir of Ambrosius Aurelianus, Ambrosius Aurelianus Brittanicus, the new emperor, had named the Bretwalda his magister militum, and that the Bretwalda had sent him to offer Aulus Hectorius the opportunity to serve him in the emperor’s army. Caius Hectorius and Aulus both knew Brittanicus in their youth: a vain, pompous, cruel, and cowardly boy. Aulus gathered his knights to discuss their options. By uniting their enemies, the Bretwalda did bring peace to the island, but Caratacus Strongarm warned that such a peace would only be one that benefitted the Bretwalda’s warriors. To refuse to serve the Bretwalda would mean declaring open rebellion against Brittanicus, Ambrosius’s lawful heir. He gave his commanders time to consider their decisions.
When they reconvened, each of them agreed to rebel against Brittanicus and the Bretwalda. Caratacus, having found friends in Caius and Badiovirus over the winter, revealed that the Bretwalda had approached him, inviting him to join his forces, revealing himself in the process. Caratacus revealed the identity of their enemy as Ælle, King of the South Saxons.
Osgar had not come to Vinovium alone, though. He had several Saxon warbands waiting in the countryside nearby. The knights carefully coordinated the fort’s defense in relative secret, extracting the garrison from the blackmail the Saxons had used against their commander and Einion ap Mark. They also discovered that Ælle had made an arrangement with Gartnaich, who brought even more Picts to the battle, in exchange for Gwenhwyfar. Lugh Striking-Hand slipped out of the fort at night with Gwenhwyfar and hid her with a friend living in a nearby estate, then found Gartnaich and convinced him to let Gwenhwyfar marry Aulus, and thus bring peace to Pictland. Gartnaich agreed, but vowed to watch closely, and that he would take Gwenhwyfar back if Lugh’s suggestion proved fruitless.
In the morning, Aulus, bearing his shield painted with the image of the Virgin for the first time, led his army against the Saxons. They repelled the attack, and Aulus’s warband spent much of the day running down Osgar’s personal retinue.
The battle marked a critical moment, like Julius Caesar crossing the Rubicon — Aulus and his knights were now irrevocably in defiance of the Bretwalda Ælle and his imperial puppet, Brittanicus. The army marched towards Eboracum, where Constantine’s troops acclaimed him emperor over a hundred years before, to determine the future they were going to fight for.