 In 1063, Barisone gave a gift of a large territory and two churches, including the Byzantine church of Nostra Segnora de Mesumundu and that of Sant'Elia di Montesanto, to the abbey of Montecassino and asked the abbot Desiderius of Benevento to send twelve monks to establish the Benedictine rule on the island of Sardinia.Desiderius sent them, via Gaeta, with books, relics, and other religious and cultural items.However, determined to maintain a religious monopoly in Sardinia, the Pisan archdiocese attacked the monks at sea off the Giglio Island, where four died.