He expounded that the throne of Milan should originally have been Lodovico's, and never Galeazzo Maria's (Gian Galeazzo's father), because the latter was born before Francesco Sforza had become Duke of Milan, whereas Lodovico was born when he already was so.
The obsequies of Gian Galeazzo completed, Charles pushed on.

From Florence he issued his manifesto, and although this confined itself to claiming the kingdom of Naples, and said no word of punishing the Pope for his disobedience in crowning Alfonso and being now in alliance with him, it stirred up grave uneasiness at the Vatican.
The Pope's position was becoming extremely difficult; nevertheless, he wore the boldest possible face when he received the ambassadors of France, and on December 9 refused to grant the letters patent of passage through the Pontifical States which the French demanded.

Thereupon Charles advanced threateningly upon Rome, and was joined now by those turbulent barons Orsini, Colonna, and Savelli.
Alexander VI has been widely accused of effecting a volte-face at this stage and betraying his Neapolitan allies; but his conduct, properly considered, can hardly amount to that.

What concessions he made to France were such as a wise and inadequately supported man must make to an army ninety thousand strong.

To be recklessly and quixotically heroic is not within the function of Popes; moreover, Alexander had Rome to think of, for Charles had sent word that, if he were resisted he would leave all in ruins, whereas if a free passage were accorded him he would do no hurt nor suffer any pillage to be done in Rome.
So the Pope did the only thing consistent with prudence: he made a virtue of necessity and gave way where it was utterly impossible for him to resist.