While literature is replete with tales of King Arthur and his knights of the Round Table, pinpointing the identity of the real King Arthur has proven to be a vexing chore for historians. In an attempt to separate the fiction from the history, Frank D. Reno demonstrated in an earlier McFarland book that the true King Arthur was a Celtic king of post-Roman Britain who lived in the late fifth and early sixth century. In an effort to further authenticate the Celtic Arthur as the legendary king, in this work the author examines the roles of six major figures of the period from AD 383 to 518: Vortimer, Vitalinus, Cunedda, Cerdic, Octha and Mordred. Through an extensive analysis of Arthur"s 12 battles listed in the "Historia Brittonum", he explores not only the influences of the King"s allies, but also the switch of allegiance by some Britons who joined forces with Arthur"s English and German enemies. A battle list is included, providing possible geographical locations for each of the battles, including a new site for Arthur"s fateful battle at Camlann, determined by the author"s research.