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Desiderius(dēsĭdēr`ēəs), d. after 774, last Lombard king in Italy (756–74). The duke of Tuscany, he was chosen king with the support of the pope and of Pepin the Short, who was king of the Franks and whose son Charles (later Emperor Charlemagne) married Desiderius's daughter. Desiderius's alliance with his son-in-law Duke Tassilo of Bavaria and his subsequent interference in Roman affairs incensed Charlemagne, who repudiated (771) his wife and provoked open conflict. Desiderius responded by supporting the claims of the children of Charlemagne's brother Carloman (d. 771), by attacking Pope Adrian IAdrian I,
d. 795, pope (772–95), a Roman; successor of Stephen IV. At Adrian's urging, Charlemagne crossed the Alps and defeated the Lombard king, Desiderius, who had annexed papal territory. That defeat marked the end of the Lombard kingdom.
..... Click the link for more information. , and by occupying several papal cities. Charlemagne invaded (773) Italy, captured (774) Desiderius at Pavia after a long siege, and proclaimed himself king of the Lombards. Desiderius was forced to retire to a monastery at Liège.