As with several other sites such as Camelot, Avalon, and Badon, the location of King Arthur's battle (that is, Ambrosius Aurelianus’s battle) at Camlann is also controversial . As the HTML on this site mentions, one common location is on Hadrian's Wall at Birdoswald overlooking the River Irthing. Etymological clues, although at times they are unreliable and inaccurate, offer suppositions of Camlann's geographic location. However, Camboglanna is outside Ambrosius’s's arena if one accepts the Historia Brittonum's declaration that Ambrosius--not Arthur--was fighting against Hengist and the Anglians. What makes more sense is that Arthur's battle-list is more logically attributed to Lucius Artorius Castus, with the Battle of Badon being an exception. In The Heroic Age Linda Malcor, based on the assumption that the battle-list attributed to Arthur in the Historia Brittonum should rightly be credited to Lucius Artorius, traces his itinerary to the north along Hadrian's Wall and to the overlook of the River Irthing, Lucius Artorius’s battleground, not Ambrosius’s.
In The Quest for King Arthur, Geoffrey Ashe puts forth two different possibilities in his presentation of Camlann which I quoted in The Historic King Arthur. First, "The River Camel [in Cornwall near Slaughter Bridge] is often stated to be the scene of the battle of Camlann." Then, on the very next page, he selects--as the best of three possibilities for the Camlann site--Camboglanna in Cumberland, "better than the other two etymologically but perhaps not historically." The first is a reference to literary tradition and Geoffrey of Monmouth, the second a speculation offered by a number of different scholars.
In a different book, The Discovery of King Arthur, which embraces the thesis that Arthur was a fifth- rather than a second- century figure, Ashe follows the same pattern of mixing literary tradition and historical speculation without making a clear distinction. After some initial hesitation, he becomes more explicit about the location of Camlann, voicing a different possibility from that in The Quest for Arthur's Britain:
The real location is not clear. Camlann probably means "crooked
bank,." and more than one river has the "crooked" element in its
name. The only place called Camlan today is a valley in Merioneth in
northwestern Wales with a small river flowing down it.
More than likely, he meant that Camboglanna (not Camlann) should be defined as "crooked bank," and that Merioneth is the territory adjacent to Gwynedd. He refers to a valley by the name of Camlann--spelled with one "n" rather than two--unlocatable on modern maps, although there is an Afon Gamlan about five miles north of Dolgellau.