He was chosen to be duke by the Spoletan nobility without the assent of the king.
While Pope Stephen II was working to give the kingdom into the hands of Desiderius, he also worked to give the homage of the Duchies of Benevento and Spoleto to King Pepin the Short of the Franks.
Alboin and Liutprand of Benevento commended their duchies to the Frankish king, who did not ask for it.
Desiderius marched on and destroyed Spoleto and Benevento and Alboin was captured; Liutprand fled.
Desiderius himself took up the exercise of ducal power in Spoleto.