For 10 points, name this eldest son of Pepin the Short, the founder of the Carolingian Dynasty.
This man's forces killed captives in the Massacre of Verden while fighting warriors led by Widukind. His son conquered a fortress called the Ring of the Avars in his defeat over the Avar Khaganate. This ruler married Desiderata, daughter of the king of the Lombards, and he invited such scholars as Peter of Pisa and (*) Alcuin of York to join his court. Some of this man's chief followers were killed at Roncevaux Pass by the Basques. He was succeeded by his son Louis the Pious and his territories were ultimately divided in the Treaty of Verdun. On Christmas Day in 800, this man was crowned emperor by Pope Leo III. For 10 points, name this eldest son of Pepin the Short, the founder of the Carolingian Dynasty.
This man's forces killed captives in the Massacre of Verden while fighting warriors led by Widukind.
Charlemagne [or Charles the Great or Charles I]