Pietro Della Vigna wrote a law code for this polity called the Liber Augustalis, also known as the Constitutions of Melfi. The Treaty of Anagni ended a crusade declared by Pope Martin IV in an attempt to make this region a papal fief. The Peace of Caltabellotta resulted in Charles the Lame renouncing the throne of this place, after which it was ruled as Trinacria by Frederick III. An earlier conflict over control of this territory featured the exploits of Roger of Lauria, who fought against Philip the Bold, and that conflict began when Charles of Anjou was ousted in favor of Peter III of Aragon by a riot occurring during church services. For 
Pietro Della Vigna wrote a law code for this polity called the Liber Augustalis, also known as the Constitutions of Melfi. The Treaty of Anagni ended a crusade declared by Pope Martin IV in an attempt to make this region a papal fief. The Peace of Caltabellotta resulted in Charles the Lame renouncing the throne of this place, after which it was ruled as Trinacria by Frederick III. An earlier conflict over control of this territory featured the exploits of Roger of Lauria, who fought against Philip the Bold, and that conflict began when Charles of Anjou was ousted in favor of Peter III of Aragon by a riot occurring during church services. For 10 points, name this island whose namesake Vespers saw it broken from the kingdom of Naples.
Pietro Della Vigna wrote a law code for this polity called the Liber Augustalis, also known as the Constitutions of Melfi.
{Sicily}