Angelus Pacis explores the largely overlooked legation of Cardinal Giovanni Gaetano Orsini, who served as Pope John XXII’s legatus a latere to central Italy from 1326 to 1334. Orsini's appointment constituted a break from the Avignon papacy's traditional reliance on Gallic agents in Italy — a fact which contributed significantly to both the successes and the failures of his legation. The book examines Avignonese papal policy in Italy and the peculiar circumstances that necessitated Orsini's legation; Orsini's powerful Roman family; the nature of the legatine power he wielded; his campaigns in Tuscany and the Papal States; his provocative signoria in Rome; his reform initiatives; and the reasons underlying the ultimate failure of his mission.