In the latter city Charles was met by an ambassador of Spain--Antonio da Fonseca.

Ferdinand and Isabella were moved at last to befriend their cousins of Naples, whom all else had now abandoned, and at the same time serve their own interests.

Their ambassador demanded that Charles should abandon his enterprise and return to France, or else be prepared for war with Spain.
It is eminently probable that Cesare had knowledge of this ultimatum to Charles, and that his knowledge influenced his conduct.

However that may be, he slipped out of Velletri in the dead of that same night disguised as a groom.

Half a mile out of the town, Francesco del Sacco, an officer of the Podesta of Velletri, awaited him with a horse, and on this he sped back to Rome, where he arrived on the night of the 30th.