Piero, suddenly drew back. Sforza found out how this change had come
about, and learned that it was Piero's influence that had overmastered
his own. He could not disentangle the real motives that had promised the
change, and imagined there was some secret league against himself: he
attributed the changed political programme to the death of Lorenzo dei
Medici. But whatever its cause might be, it was evidently prejudicial to
his own interests: Florence, Milan's old ally, was abandoning her for
Naples. He resolved to throw a counter weight into the scales; so,
betraying to Alexander the policy of Piero and Ferdinand, he proposed to
form a defensive and offensive alliance with him and admit the republic
of Venice; Duke Hercules III of Ferrara was also to be summoned to
pronounce for one or other of the two leagues. Alexander VI, wounded by
Ferdinand's treatment of himself, accepted Ludovico Sforza's proposition,
and an Act of Confederation was signed on the 22nd of April, 1493, by
which the new allies pledged themselves to set on foot for the
maintenance of the public peace an army of 20,000 horse and 6,000
infantry.

Ferdinand was frightened when he beheld the formation of this league; but
he thought he could neutralise its effects by depriving Ludovico Sforza
of his regency, which he had already kept beyond the proper time, though
as yet he was not strictly an usurper. Although the young Galeazzo, his
nephew, had reached the age of two-and-twenty, Ludovico Sforza none the
less continued regent. Now Ferdinand definitely proposed to the Duke of
Milan that he should resign the sovereign power into the hands of his
nephew, on pain of being declared an usurper.

This was a bold stroke; but there was a risk of inciting Ludovico Sforza
to start one of those political plots that he was so familiar with, never
recoiling from any situation, however dangerous it might be. This was