Camelot was a near-mythic kingdom in England that existed in the 6th century CE. The Castle Camelot was home to Arthur Pendragon and his legendary Knights of the Round. It was an attempt by the great and powerful Merlyn to forge a stable kingdom on Britannia, one that could guarantee the stability of the bridge to Avalon and the realm of Otherworld.
The tales of Camelot were manyfold. King Arthur was recognized as the lord of the land when he drew the legendary sword Caliburn from a stone set at the heart of Castle Winchester. He gathered the best and bravest knights from all over Britain and much of Europe to his court. The Lady of the Lake gave Arthur the indestructible sword Excalibur, held in trust until a worthy champion came to wield it.
Camelot became known as a land of great heroic virtues and terrific gallantry. Launcelot, Percival, Galahad and others helped create the trappings of chivalric custom through their courageous deeds.
The principle antagonist of Camelot was the ancient Atlantean witch Morgan le Fay. She saw her nephew Mordred as the rightful heir to the crown of England and spent much of her time conspiring with her half-sister Morgause to try and put Mordred on the throne. When those plains failed to come to fruition, Morgan sought out the Darkhold and the forbidden magics of ancient Chthon. The Knights of the Round were able to foil her plans and trap Chthon under Mount Wundagore with the help of allies from many far-flung lands, including the demon Etrigan.
Camelot succumbed not to external foes but internal discord. Queen Guinevere and Sir Launcelot had a torrid affair that broke the Round Table into deep infighting. Galahad quit the Knights to become the first Captain Britain. Morgause stole Excalibur's sheathe and flung it into a tributary of the waters of Faerie, and her son Mordred wounded his father Arthur unto death in a battle. Excalibur was returned to the Tuatha de Danaan and Caliburn placed in the trust of the Captain Britain Corps until such time a worthy king was needed to protect Britain and Avalon from evil once more.