The cardinals assembled at Perugia after the death of Nicholas IV in April of 1292. Morrone, well known to the cardinals as a Benedictine hermit, sent the cardinals a letter warning them that divine vengeance would fall upon them if they did not quickly elect a pope. Latino Malabranca, the aged and ill dean of the College of Cardinals cried out, "In the name of the Father, the Son, and the Holy Ghost, I elect brother Pietro di Morrone." The cardinals promptly ratified Malabranca's desperate decision. When sent for, Morrone obstinately refused to accept the Papacy, and even, as Petrarch says, attempted flight, till he was at length persuaded by a deputation of cardinals accompanied by the kings of Naples and Hungary. Elected July 7, 1294, he was crowned at S. Maria di Collemaggio in the city of Aquila (now called L'Aquila) in the Abruzzi, August 29. He issued two decrees -- one confirming that of Gregory X, which orders the shutting of the cardinals in conclave; the second declaring the right of any Pope to abdicate the Papacy -- a right he, at the end of five months and eight days, proceeded to exercise at Naples on December 13 1294.
In the formal instrument of his renunciation he recites as the causes moving him to the step, "the desire for humility, for a purer life, for a stainless conscience, the deficiencies of his own physical strength, his ignorance, the perverseness of the people, his longing for the tranquility of his former life"; and having divested himself of every outward symbol of dignity, he retired to his old solitude.
He was not allowed to remain there, however. His successor, Boniface VIII, sent for him, and finally, despite desperate attempts of the late Pope to escape, got him into his hands, and imprisoned him in the castle of Fumone near Ferentino in Campagna, where, after languishing for ten months in that infected air, he died on May 19, 1296. Some historians believe he might have been murdered by Boniface VIII, and indeed his skull has a suspicious hole. He was buried at Ferentino, but his body was subsequently removed to Aquila, where it still lies. Many early commentators and scholars of Dante have thought that the poet stigmatized Celestine V in the enigmatical verse Colui che fece per viltade il gran rifiuto, Who made by his cowardice the grand refusal (Inferno, III, 59). Most later commentators, however, refute such an identification and believe Dante might have intended the verse to refer to someone else. Celestine V, like the first of the name, is recognized by the Church as a saint. No subsequent pope has taken the name 'Celestine.'
Although generally deemed a saintly man he has received some criticism. As mentioned above, in the Divine Comedy Dante might have placed him near the gates of Hell, but not in Hell precisely, because he deemed him indecisive. Also because his resignation led to the reign of Boniface VIII. Others felt that his austere hermit-like life made him naive and unsuited for the job as Pope. This criticism may be more fair as he himself wish to retire due to the pressure. Others argue the opposite: his abdication of such immense power, wealth, and material comfort, in pursuit of austere, humble surroundings, was a most pious and admirable sacrifice demonstrating Celestine's profound and rare degree of spiritual fortitude and virtue.
Another thing he did which may be noted (it seems to be the only instance in the history of the Church) is that he empowered one Francis of Apt, a Franciscan friar, to confer the clerical tonsure and minor orders on Lodovico (who would later become Bishop of Toulouse), son of the king of Sicily. However, this decree seems not to have been carried out.