Eric of Friuli was this man's brother in law.
According to one source, this man spared a rival because that man had a vision while attending mass in this man's camp. Eric of Friuli was this man's brother in law. He sieged Pavia after his sister-in-law Gerberga ran away, and in that siege he defeated Desiderius, a king of the Lombards. Another battle fought by this man saw him get slaughtered by the Vascones after marching across the Pyrenees in an attempt to take Zaragoza. That loss is commemorated in an epic in which the horn Oliphaunt is blown. Biographers of this man include the Monk of St Gall and Einhard. For ten points, name this Carolingian ruler who was crowned Emperor of the Romans by Pope Leo III, a "great" Frankish King.
According to one source, this man spared a rival because that man had a vision while attending mass in this man's camp.
{Charlemagne} (ACCEPT: {Charles the Great}, prompt on Charles)