In 1517 he led a costly war that succeeded in securing his nephew Lorenzo di Piero de' Medici as Duke of Urbino, but reduced papal finances.

Leo rejected the Protestant Reformation, and his Papal bull of 1520, Exsurge Domine, condemned Luther's condemnatory stance, rendering ongoing communication difficult.

Under his reign, Marco Girolamo Vida began composing at the Pope's request a Virgilian Latin epic poem about the life of Jesus called the Christiad, progress was made on the rebuilding of St. Peter's Basilica, and artists such as Raphael decorated the Vatican rooms.

His father, Lorenzo de Medici, was worried about his character early on and wrote a letter to Giovanni to warn him to avoid vice and luxury at the beginning of his ecclesiastical career.

[3] His father prevailed on his relative Pope Innocent VIII to name him cardinal of Santa Maria in Domnica on 9 March 1489 when he was age 13,[4] although he was not allowed to wear the insignia or share in the deliberations of the college until three years later.

Meanwhile, he received an education at Lorenzo's humanistic court under such men as Angelo Poliziano, Pico della Mirandola, Marsilio Ficino and Bernardo Dovizio Bibbiena.

He returned to Rome to participate in the conclave of 1492 which followed the death of Innocent VIII, and unsuccessfully opposed the election of Cardinal Rodrigo Borgia as Pope Alexander VI.

He subsequently made his home with his elder brother Piero in Florence throughout the agitation of Girolamo Savonarola and the invasion of Charles VIII of France, until the uprising of the Florentines and the expulsion of the Medici in November 1494.

In 1503 he welcomed the accession of Pope Julius II to the pontificate; the death of Piero de' Medici in the same year made Giovanni head of his family.

He had named them Roman patricians; the latter he had placed in charge of Florence; the former, for whom he planned to carve out a kingdom in central Italy of Parma, Piacenza, Ferrara and Urbino, he had taken with himself to Rome and married to Filiberta of Savoy.

Among the nominations were such notable men such as Lorenzo Campeggio, Giovanni Battista Pallavicino, Adrian of Utrecht, Thomas Cajetan, Cristoforo Numai and Egidio Canisio.

A truce was to be proclaimed throughout Christendom; the pope was to be the arbiter of disputes; the emperor and the king of France were to lead the army; England, Spain and Portugal were to furnish the fleet; and the combined forces were to be directed against Constantinople.

Papal diplomacy in the interests of peace failed, however; Cardinal Thomas Wolsey made England, not the pope, the arbiter between France and the Empire; and much of the money collected for the crusade from tithes and indulgences was spent in other ways.

[11] In 1519 Hungary concluded a three years' truce with Selim I, but the succeeding sultan, Suleiman the Magnificent, renewed the war in June 1521 and on 28 August captured the citadel of Belgrade.

[11] A further papal bull of 15 June 1520, Exsurge Domine or Arise, O Lord, condemned forty-one propositions extracted from Luther's teachings, and was taken to Germany by Johann Eck in his capacity as apostolic nuncio.

The pope had repeatedly used the rich northern benefices to reward members of the Roman curia, and towards the close of the year 1516, he sent the impolitic Giovanni Angelo Arcimboldi as papal nuncio to Denmark to collect money for St Peter's.

King Christian II took advantage of the growing dissatisfaction of the native clergy toward the papal government, and of Arcimboldi's interference in the Swedish revolt, to expel the nuncio and summon Lutheran theologians to Copenhagen in 1520.

Christian approved a plan by which a formal state church should be established in Denmark, all appeals to Rome should be abolished, and the king and diet should have final jurisdiction in ecclesiastical causes.

[16] He is said to have stated, "Let us enjoy the papacy since God has given it to us",[17] Ludwig von Pastor says that it is by no means certain that he made the remark; and historian Klemens Löffler says that "the Venetian ambassador who related this of him was not unbiased, nor was he in Rome at the time.

In the 17th century it was estimated that 300 or 400 writers, more or less, reported (on the authority of a single polemical anti-Catholic source) a story that when someone had quoted to Leo a passage from one of the Four Evangelists, he had replied that it was common knowledge "how profitable that fable of Christe hath ben to us and our companie".

I am not so foolish to attack one whom everybody praises ...[25]The final report of the Venetian ambassador Marino Giorgi supports Hume's assessment of affability and testifies to the range of Leo's talents.

[26] Bearing the date of March 1517 it indicates some of his predominant characteristics:[11] The pope is a good-natured and extremely free-hearted man, who avoids every difficult situation and above all wants peace; he would not undertake a war himself unless his own personal interests were involved; he loves learning; of canon law and literature he possesses remarkable knowledge; he is, moreover, a very excellent musician.

One case concerned the conceited improvisatore Giacomo Baraballo, Abbot of Gaeta, who was the butt of a burlesque procession organised in the style of an ancient Roman triumph.

[43] Historians have dealt with the issue of Leo's sexuality at least since the late 18th century, and few have given credence to the imputations made against him in his later years and decades following his death, or else have at least regarded them as unworthy of notice; without necessarily reaching conclusions on whether he was homosexual.

[45] Joseph McCabe accused Pastor of untruthfulness and Vaughan of lying in the course of their treatment of the evidence, pointing out that Giovio and Guicciardini seemed to share the belief that Leo engaged in "unnatural vice" (homosexuality) while pope.

[46] Leo X made charitable donations of more than 6,000 ducats annually to retirement homes, hospitals, convents, discharged soldiers, pilgrims, poor students, exiles, cripples, and the sick and unfortunate.

Martin Luther's 95 Theses, otherwise entitled "Disputation on the Power and Efficacy of Indulgences", was posted on a Church door in Wittenberg, Germany in October 1517 just seven months after the Lateran V was completed.

But Pope Leo X's attempt to prosecute Luther's teaching on indulgences, and to eventually excommunicate him in January 1521, did not get rid of Lutheran doctrine but had the opposite effect of further splintering the Western church.

To remain financially solvent, the Pope resorted to desperate measures: instructing his cousin, Cardinal Giulio de' Medici, to pawn the Papal jewels; palace furniture; tableware; and even statues of the apostles.

Additionally, Leo sold cardinals' hats; memberships to a fraternal order he invented in 1520, the Papal Knights of St. Peter and St. Paul; and borrowed such immense sums from bankers that upon his death, many were ruined.