| Papal conclave September 1503 | |
|---|---|
| Dates and location | |
| September 1503 Apostolic Palace, Papal States | |
| Key officials | |
| Dean | Giuliano della Rovere |
| Camerlengo | Raffaele Riario |
| Protodeacon | Francesco Todeschini-Piccolomini |
| Election | |
| Candidates | Georges d'Amboise, Giuliano della Rovere, Francesco Todeschini Piccolomini |
| Ballots | 2 |
| Elected pope | |
| Francesco Todeschini Piccolomini Name taken: Pius III | |
 | |
The September 1503 papal conclave elected Pope Pius III to succeed Pope Alexander VI. Due to the Italian Wars, the College of Cardinals was surrounded by three potentially hostile armies, loyal to Louis XII of France, Ferdinand II of Aragon, and Cesare Borgia (the cardinal-nephew and illegitimate son of Alexander VI).
The participation of thirty-nine cardinals, made possible by the delay of the funeral of Alexander VI, made the conclave the largest in history, up to that time, in terms of the number of electors. There were 21 Italian cardinals, 11 Spanish, and 7 French. A convergence of factors undid years of planning by Louis XII and his predecessor Charles VIII of France to promote the candidacy of Georges d'Amboise. After receiving far fewer votes than expected on the first ballot due to the independent candidacy of Giuliano della Rovere and the loss of control of the Spanish cardinals by Cesare Borgia, d'Amboise threw his support to Cardinal Francesco Piccolomini, who was elected Pius III on the second ballot despite receiving only four on the first.