Complex sentence: The Basque would continue their rebellion to Carolingian rule until the appointment William of Orange, who would dissolve their rebellion after capturing and exiling Lupo's son and Basque leader Adalric in 790.
Split into simpler sentences: The Basque would continue their rebellion to Carolingian rule until the appointment William of Orange that will dissolve their resistance. William fought defeated the Basque after capturing and exiling Lupo's son and Basque leader Adalric in 790.