<b> <i>Electione de eo canonice celebrata</i> </b>

Abstract This article analyses Alfonso X of Castile and Leon’s self-presentation in his documentation for the fecho del imperio , his bid to become Holy Roman Emperor during the Great Interregnum. The Castilian king was in open competition with another would-be emperor, Richard of Cornwall, but could muster three possible arguments for legitimacy to deploy within his imperial propaganda against his English rival: Swabian blood (on his mother’s side), Crusader and Spanish imperial heritage (on his father’s side), and his election as King of the Romans by the German princes in early 1257. Of the three, Richard could boast only the third, as he had also been elected rex Romanorum by other prince-electors on the same occasion. Contrary to most scholars’ beliefs, however, Alfonso X chose to rely on the argument of his imperial election rather than the other two in his documentation. Alfonso’s narrative is based not on rhetoric and ideals, but rather on specific legal arguments.