[3] He was born at Naples into one of the city's most ancient and distinguished families, a younger son of Giovanni Alfonso Carafa, count of Montorio, and his countess, Caterina Cantelma.

He then fought under the Alfonso d'Avalos, Marchese del Vasto, in Lombardy and Piedmont, and under Ottavio Farnese, Duke of Parma, in Flanders and Germany, fighting Protestants in the name of the Emperor.

[6] He was subsequently exiled from Naples in 1545 for murder and banditry and, having withdrawn to Benevento, was embroiled in another assassination,[7] and was then alleged to have perpetrated the massacre of Spanish soldiers as they recuperated in a hospital in Corsica.

His tenure as Cardinal Nephew was not a great success, and he and Paul IV effectively brought the Papacy to a humiliating defeat against the Spanish that nearly resulted in another Sack of Rome.

Carlo's government proved unpopular and he developed a reputation for avarice, cruelty and licentiousness, as well as for homosexual sodomy (Paul had chastised Cardinal Ghisleri for not sharing his suspicions on this latter point).