The historical basis for King Arthur was long debated by scholars. One school of thought, citing entries in the "Historia Brittonum" ("History of the Britons") and "Annales Cambriae" ("Welsh Annals"), saw Arthur as a genuine historical figure, a Romano-British leader who fought against the invading Anglo-Saxons some time in the late 5th to early 6th century. The "Historia Brittonum", a 9th-century Latin historical compilation attributed in some late manuscripts to a Welsh cleric called Nennius, contains the first datable mention of King Arthur, listing twelve battles that Arthur fought. These culminate in the Battle of Badon, where he is said to have single-handedly killed 960 men. Recent studies, however, question the reliability of the "Historia Brittonum". The other text that seems to support the case for Arthur's historical existence is the 10th-century "Annales Cambriae", which also link Arthur with the Battle of Badon. The "Annales" date this battle to 516–518, and also mention the Battle of Camlann, in which Arthur and Medraut (Mordred) were both killed, dated to 537–539. These details have often been used to bolster confidence in the "Historia"'s account and to confirm that Arthur really did fight at Badon. Problems have been identified, however, with using this source to support the "Historia Brittonum"s account. The latest research shows that the "Annales Cambriae" was based on a chronicle begun in the late 8th century in Wales. Additionally, the complex textual history of the "Annales Cambriae" precludes any certainty that the Arthurian annals were added to it even that early. They were more likely added at some point in the 10th century and may never have existed in any earlier set of annals. The Badon entry probably derived from the "Historia Brittonum". This lack of convincing early evidence is the reason many recent historians exclude Arthur from their accounts of sub-Roman Britain. In the view of historian Thomas Charles-Edwards, "at this stage of the enquiry, one can only say that there may well have been an historical Arthur [but ...] the historian can as yet say nothing of value about him". These modern admissions of ignorance are a relatively recent trend; earlier generations of historians were less sceptical. The historian John Morris made the putative reign of Arthur the organising principle of his history of sub-Roman Britain and Ireland, "The Age of Arthur" (1973).