were collectively canonized as saints by the Roman Catholic Church on 12 May 2013. Their remains are claimed to be stored today in Otranto Cathedral and in the church of Santa Caterina a Formiello in Naples. The traditional Christian historiography has come under criticism by later historians. Recent scholarship has questioned whether conversion was imposed as a condition for clemency. Although one contemporary Ottoman account justifies the massacre on religious grounds, Ilenia Romana Cassetta writes that it seems rather to have been a punitive action whose goal was intimidation. Stalled advance In August, 70 ships of the fleet attacked Vieste. On 12 September, the Monastero di San Nicholas di Casole, which accommodated one of the richer libraries of Europe, was destroyed. By October attacks had been conducted against the coastal cities of Lecce, Taranto, and Brindisi. However, due to lack of supplies, the Ottoman commander, Gedik Ahmed Pasha, did not consolidate his force's advance. Instead he returned with most of his troops to Albania leaving a garrison of 800 infantry and 500 sipahi behind to defend Otranto. It was assumed he would return with his army after the winter. Catholic response Since it was only 27 years after the fall of Constantinople, there was some fear that Rome would suffer the same fate. Plans were made for the Pope and citizens of Rome to evacuate the city. Pope Sixtus IV repeated his 1471 call for a crusade. Several Italian city-states, Hungary, and France responded positively to this. The Republic of Venice did not, as it had signed an expensive peace treaty with the Ottomans in 1479. In April 1481 Sixtus IV called for an Italian crusade to liberate the city, and Christian forces besieged Otranto in May. An army was raised by King Ferdinand I of Naples to be led by his son Alfonso, Duke of Calabria. A contingent of troops was provided by King Matthias Corvinus of Hungary. Recapture Between August and September, King Ferdinand of Naples, with the help of his cousin Ferdinand the Catholic and the Kingdom of Sicily, tried unsuccessfully to recapture Otranto. The Christian forces besieged the city on 1 May 1481. Turkish Sultan Mehmed the Conqueror was preparing for a new campaign on Italy but he lost his life on 3 May. Ongoing succession issues prevented the Ottomans from sending reinforcements to Otranto. After the negotiation with the Christian forces, the Turks surrendered in