Emmanuel Philibert, Duke of Savoy
Belli served the Holy Roman Empire as the commander of Imperial forces in Piedmont. In 1560, Emmanuel Philibert, Duke of Savoy, named him a councillor of state. He is most notable for his book, "De re militari et de bello" (1563) which was one of the most comprehensive treatments of military law and the rules of war that had been written up to that time.