He was a page at the court of Philip II, took part in the campaign in Portugal under the Duke of Alba and in 1582 was given supreme command over the Spanish troops.
He was then made governor and Captain General of Milan, where he spread fear among the Italiannobility, especially the Venetians through his policies and use of the army. In 1599, he entered into a treaty with the Count of Savoy and assisted in the conspiracy of Biron. Under his rule a famous fortress, named after him and now ruined, was built to guard the border against the Grisons near Colico.