The life at S. Sophia was not strict enough for the young monk, who betook himself first to the island monastery of Tremite San Nicolo[3] in the Adriatic and in 1053 to the hermits at Majella in the Abruzzi.

In 1057 Pope Stephen IX, who had retained the abbacy of Monte Cassino, came to visit and at Christmas, believing himself to be dying, ordered the monks to elect a new abbot.

Having obtained a safe-conduct from Robert Guiscard, the Norman Count (later Duke) of Apulia, he returned to his monastery and was duly installed by Cardinal Humbert on Easter Day 1058.

[5] Peter the Deacon gives[6] a list of some seventy books Desiderius had copied at Monte Cassino, including works of Augustine of Hippo, Ambrose, Bede, Basil of Caesarea, Jerome, Gregory of Nazianzus and Cassian, the histories of Josephus, Paul Warnfrid, Jordanes and Gregory of Tours, the Institutes and Novels of Justinian, the works of Terence, Virgil and Seneca, Cicero's De natura deorum, and Ovid's Fasti.

So great was his reputation with the Holy See that he "...was allowed by the Roman Pontiff to appoint Bishops and Abbots from among his Benedictine brethren in whatever churches or monasteries he desired, of those that had lost their patron".

In 1082 he visited the Italian king and future Holy Roman Emperor Henry IV at Albano, while the troops of the Imperialist antipope Clement III were harassing the pope from Tivoli.

Finding, however, that they were bent on forcing the papal dignity upon him, he fled to Monte Cassino, where he busied himself in exhorting the Normans and Lombards to rally to the support of the Holy See.

On 23 May a great meeting was held in the deaconry of St. Lucy, and Desiderius was again importuned to accept the papacy but persisted in his refusal, threatening to return to his monastery in case of violence.

The Roman consul Cencius now suggested the election of Odo, Cardinal-Bishop of Ostia (afterwards pope Urban II), but this was rejected by some of the cardinals on the grounds that the translation of a bishop was contrary to ecclesiastical law.

[9] Four days later, pope and cardinals had to flee from Rome due to the presence of the Antipope Clement III,[10] and at Terracina, in spite of all protests, Victor laid aside the papal insignia and once more retired to Monte Cassino, where he remained nearly a whole year.

In the middle of Lent 1087, the pope-elect assisted at a council of cardinals and bishops held at Capua as "Papal vicar of those parts" (letter of Hugh of Lyons) together with the Norman princes, Cencius the Consul and the Roman nobles.

In August 1087, a synod was held at Benevento which renewed the excommunication of the Antipope Clement III, the condemnation of lay investiture, proclaimed a crusade against the Saracens in northern Africa, and anathematised Hugh of Lyons and Richard, Abbot of Marseilles.

In his De Viris Illustribus Casinensibus, Peter the Deacon ascribes to him the composition of a "Cantus ad B. Maurum" and letters to King Philip I of France and to Hugh of Cluny, which no longer exist.

The cult of Blessed Victor III seems to have begun not later than the pontificate of Pope Anastasius IV, about six decades after his death (Acta Sanctorum, Loc.