Letters to the missing Italian cardinals follow on August 20 declaring the papal throne vacant (sede vacante).

Then at Fondi, secretly supported by the king of France, the French cardinals proceed to elect Robert of Geneva as Pope on September 20.

Robert, a militant cleric who had succeeded Albornoz as commander of the papal troops, takes the name Clement VII, beginning the Western Schism, which will divide Catholic Christendom until 1417.

Urban is declared excommunicated by the French antipope and is called "the Antichrist", while Catherine of Siena, defending Pope Urban, calls the cardinals "devils in human form."

Coluccio Salutati identifies the political nature of the withdrawal: "Who does not see," the Chancellor openly addresses the French cardinals, "that you seek not the true pope, but opt solely for a Gallic pontiff."