It is not known when Francesco de Arenis was born, but he was probably of Spanish origin. He was a very important figure from a political and religious point of view in the Land of Bari.
Having probably arrived in the Kingdom following Alfonso the Magnanimous, his military career was interrupted when, in 1460, he decided to become a monk. The relationship with the Crown remained strong, so much so that De Arenis obtained the priory of San Nicola di Bari from King Ferrante and the position of "giustiziere" of Terra di Bari and Terra d'Otranto.
The commission to build the Palace of Justice of Barletta (Palazzo dell'Arco) dates back to this time, and was at the expense of the royal tax authorities. He also took care of the reform of the statutes for the city, starting, at the same time as the palace, in 1473. He also held the position of archbishop of Brindisi and Oria (1477-1483). As an executioner he also faced the landing of the Turks in Otranto in 1480, when he was forced to take up arms again. Once the danger passed after the death of Muhammad II, De Arenis went back to dealing with religious issues, in particular the long-standing controversies with the archbishop of Bari, Antonio Aiello.