Brian Braddock was a brilliant scholar engaged in graduate work in physics at Thames University, London. One summers, shortly after his parents had been killed in an explosion in their laboratory at Braddock Manor, Brian went to work as a student research assistant at the Darkmoor Research Centre, a facility for secret nuclear research.

Braddock was present when the facility was attacked by the psychotic criminal known as the Reaver. Attempting to escape, Braddock ran his motorcycle off a cliff and lay near death. In a vision, the spirits of the god-wizard Merlyn and Roma, the lady of the Northern Skies, appeared to him and bade him choose one of the mystic objects they placed before him: the Amulet of Right or the Sword of Might. Braddock chose the amulet, and was bombarded with mystical energy. The patron spirits decreed that Braddock would be Britain's champion, and gifted him with a mystic star-scepter to enhance his fighting skills. Thus, Braddock became Captain Britain.

Keeping his true identity secret, Captain Britain began a career of battling menaces to his country. As the Mutant-Human war escalated in America, Captain Britain made sure his British shores were free of conflict, but Brian had no ill will towards mutants. Both his sister and brother appeared to have mutant abilities, and he was adamant in preaching acceptance of all species of man. The British government had other ideas, however, and entered the war. Captain Britain refused to take part and continued to protect Britain from outside threats.

When the Mutant-Human war calmed down, Britain was left relatively unscathed by outsiders. As the new ruler of the planet, Magneto, looking for a new ruler of the United Kingdom following his defeat of their armies, contacted Brian's family and asked that the oldest should take control of the United Kingdom. Because of the disappearance of Brian's older brother James Braddock Jr., Magneto asked it to Psylocke, but she stepped down in Brian's favor as she preffered traveling and adventuring, Brian accepted, fearing who Magnus would chose if he did not.

As king, Captain Britain ushered in a new age of peace and acceptance across his country. It was a new Avalon: mutants, humans, superhumans, and even some mystical creatures were accepted there. To take the fairy tale even further, Brian eventually married the elemental mutant named Meggan. She now rules by his side as his queen. The United Kingdom is well into a new golden age, all thanks to its new king, Brian Braddock.