In 1904 Adolf von Harnack proposed that Lucius of Britain, a ruler mentioned in the Liber Pontificalis as contemporaneous with Pope Eleutherius, actually was Abgar of Edessa. Harnack argued that 'Britanio' was written as an erroneous expansion for 'Britio', a citadel of Edessa. Harnack's proposal has been challenged by British archaeologist David J. Knight, who argued that Abgar of Edessa was never called Lucius of Britio/Birtha in contemporary sources.'King Lucius of Britain' by David J. Knight ()
