 The imperial title has at times been connected to (i) the independence of Spain from the Carolingian and Holy Roman Empires, (ii) the supremacy of one Spanish king over others, (iii) the king who held the Visigothic capital of Toledo or León, capital of the Visigothic "successor state", (iv) a military commander with success on the battlefield, (v) rule over multiple peoples (in an ethnic "or" religious sense), or (vi) propaganda, as in the case of Cluny or courtly historians or biographers.The first historians to seriously study the usage of the imperial title in certain documents pertaining to the kings of León were, around the same time, A. Schunter and Ernesto Mayer, who argued that it had been adopted in order to affirm the independence of the Leonese from the "restored" Roman Empire of Charlemagne (crowned by Pope Leo III in 800).Of the historical development of the imperial concept in Spain one historian writes that the "constant idea, analogous to that of the German Emperor, of the hierarchical superiority of the Spanish Emperor over the other sovereigns of Spain, the restoration of the Gothic kingdom, the submission of the nobility, the pomp of the court and the fight against Islam [...] is a mere aspiration in Alfonso III, an attempt in Ordoño II and only a reality in Alfonso VI".