Why was Abbe Faria put in prison?

From the text:

“Because in 1807 I dreamed of the very plan Napoleon tried to realize in 1811; because, like Machiavelli, I desired to alter the political face of Italy, and instead of allowing it to be split up into a quantity of petty principalities, each held by some weak or tyrannical ruler, I sought to form one large, compact, and powerful empire; and, lastly, because I fancied I had found my Cæsar Borgia in a crowned simpleton, who feigned to enter into my views only to betray me. It was the plan of Alexander VI. and Clement VII., but it will never succeed now, for they attempted it fruitlessly, and Napoleon was unable to complete his work. Italy seems fated to misfortune.”