Then, one of them dying, the other, assuming both their names, became Uther Pendragon, king of Britain.

Such was his bravery that during his reign of seven years he became overlord of all the petty kings who had meantime taken possession of various parts of England.

He was aided in this work by his prime-minister, Merlin, whose skill as a clairvoyant, magician, inventor, and artificer of all kinds of things--such as armor which nothing could damage, a magic mirror, round table, ring, and wonderful buildings--was of infinite service to his master and fired the imagination of all the poets.
There are various accounts of Arthur's birth; according to one, Uther fell in love with Gorlois' wife Igerne, who was already mother of three daughters.

Thanks to Merlin's magic arts, Uther was able to visit Igerne in the guise of her husband, and thus begot a son, who was entrusted to Merlin's care as soon as born.

Another legend declares that, after Gorlois' death, Uther Pendragon married Igerne, and that Arthur was their lawful child.