The 1513 papal conclave, occasioned by the death of Pope Julius II on 21 February 1513, opened on 4 March with twenty-five cardinals in attendance, out of a total number of thirty-one.

Negotiations after the first balloting led to the election of Cardinal Giovanni de'Medici, the son of Lorenzo the Magnificent and the de facto ruler of Florence, as Pope Leo X on the morning of 11 March.

[1] They had been participating in the Fifth Lateran Council, which had been summoned by the Pope to deal with the most pressing problems facing the Church.

[3] It was at that Session that Julius had solemnly republished his famous Bull, Cum tam divino, forbidding the buying and selling of sacred things (simony), and most especially the papal office.

It had been reported generally (the Venetians knew it on 10 February) that the Pope was suffering from a double tertian fever (malaria), and that his doctors held little hope for his recovery.

King Louis XII of France had been kept informed of the situation, and it was reported in Florence on 14 February that he had ordered the French cardinals to hasten their journey to Rome.

[6] The Imperial Ambassador, Alberto Pio de Carpi, wrote to Maximilian I that the papabili were Riario, Fieschi and Luigi d'Aragona.

[7] Cardinal Giovanni de' Medici, who had not been attending the Council, was ill in Florence with an anal fistula.

[9] Cardinal Sisto Gara della Rovere, one of Pope Julius' nephews, was so ill that he had to be carried into the Conclave, and he was given special accommodations.

[14] The first several days were spent in the regular daily Congregations on the drafting of Electoral Capitulations and regulating the procedures of the Conclave.

The Conclavists, too, were drawing up a list of demands, which included the disposal of the property of whichever Cardinal happened to be elected pope.

[20] The voting itself took place in the chapel of S. Niccolo da Bari, which was replaced by the Cappella Paolina in the reign of Pope Paul III.

Cardinal Serra received thirteen votes on the first ballot, Grosso della Rovere 8, Accolti 7, Antonio del Monte 7, Bakócz 8, Fieschi 7, Finale 5, Soderini 4, Robert Guibé 3, Adriano de Castello 3, Achille de Grassis 3, Farnese 3, Grimani 2, Bainbridge 2, Vigerio 1, Remolino 1, and Medici 1.

Trollope claims that every cardinal did such because "it is ill voting against a man to-day who is to be the despotic master of your fate and fortunes on the morrow".

The statement of unanimity is not surprising; every conclave strives to end unanimiter et concorditer, leaving no grounds for a schism.

As luck would have it, thirteen prelates had selected the same outsider, with the result that they all but elected Arborense, the most worthless nonentity present.

This narrow shave gave the Sacred College such a shock that its members determined to come to some agreement which would put matters on a more satisfactory basis for both parties.