After serving four years in one of the public offices he was appointed Chancellor and Secretary to the Second Chancery, the Ten of Liberty and Peace.

Here we are on firm ground when dealing with the events of Machiavelli's life, for during this time he took a leading part in the affairs of the Republic, and we have its decrees, records, and dispatches to guide us, as well as his own writings.

A mere recapitulation of a few of his transactions with the statesmen and soldiers of his time gives a fair indication of his activities, and supplies the sources from which he drew the experiences and characters which illustrate "The Prince." His first mission was in 1499 to Catherina Sforza, "my lady of Forli" of "The Prince," from whose conduct and fate he drew the moral that it is far better to earn the confidence of the people than to rely on fortresses.

This is a very noticeable principle in Machiavelli, and is urged by him in many ways as a matter of vital importance to princes.
In 1500 he was sent to France to obtain terms from Louis XII for continuing the war against Pisa: this king it was who, in his conduct of affairs in Italy, committed the five capital errors in statecraft summarized in "The Prince," and was consequently driven out.

He, also, it was who made the dissolution of his marriage a condition of support to Pope Alexander VI; which leads Machiavelli to refer those who urge that such promises should be kept to what he has written concerning the faith of princes.
Machiavelli's public life was largely occupied with events arising out of the ambitions of Pope Alexander VI and his son, Cesare Borgia, the Duke Valentino, and these characters fill a large space of "The Prince." Machiavelli never hesitates to cite the actions of the duke for the benefit of usurpers who wish to keep the states they have seized; he can, indeed, find no precepts to offer so good as the pattern of Cesare Borgia's conduct, insomuch that Cesare is acclaimed by some critics as the "hero" of "The Prince." Yet in "The Prince" the duke is in point of fact cited as a type of the man who rises on the fortune of others, and falls with them; who takes every course that might be expected from a prudent man but the course which will save him; who is prepared for all eventualities but the one which happens; and who, when all his abilities fail to carry him through, exclaims that it was not his fault, but an extraordinary and unforeseen fatality.
On the death of Pius III, in 1503, Machiavelli was sent to Rome to watch the election of his successor, and there he saw Cesare Borgia cheated into allowing the choice of the College to fall on Giuliano delle Rovere (Julius II), who was one of the cardinals that had most reason to fear the duke.