When Maio of Bari was assassinated at Palermo on 10 November 1160, a remarkable career was brought to a premature end. Maio, a commoner and a layman, had risen in the Sicilian curia to the rank of chancellor of the Norman kingdom under Roger II; William I had created him Grand Admiral immediately upon acceding to the throne in 1154. William lacked the political acumen of his father, and left the administration of Sicily entirely in his minister's hands. Maio asserted the prerogative of the crown against the feudal nobility and the large towns, and successfully intervened in the affairs of the Italian peninsula at a time when the struggle between emperor and pope was at its height. His strong, harsh policy provoked inevitably the implacable hatred of the Sicilian barons, who resented his tyranny and envied his power. They accused him of boundless personal ambition, even of sinister designs on the throne, and in the end organised the plot which led to his murder.
The story of his lowly birth, his immorality and wanton cruelty, reported with relish by the chronicler Hugo Falcandus, has been discredited by modern scholarship. Falcandus favoured the claims of the nobility, and did his best to blacken the reputation both of King William and of the all-powerful minister who executed the king's policy. Even Maio's enemies had to recognise his brilliant gifts. He was the son of a protoiudex of Bari, an eminently capable administrator, and a man of education. He was friendly with some of the leading scholars of the day: it was at Maio's suggestion that Henricus Aristippus translated Diogenes Laertius, and it was to Maio that Cardinal Laborans dedicated one of his legal treatises. Maio was even capable of writing a commentary on the Lord's Prayer, dedicated to his son Stephen, composed in correct and fluent Latin and showing a commendable familiarity with patristic and scholastic literature.