The utility of fortifications in early Modern Europe: Italian princes and their citadels, 1540-1640

Considerable attention has been given to the development of new and more sophisticated styles of fortification which spread across early modern Europe, and to the assumed impact of such developments on the character of war and international relations. However, by taking at face value the rhetoric of impregnability attached to massive fortification projects, historians have missed the essential point that fortresses could succeed in their defensive purpose only in conjunction with field armies able to relieve the garrison placed under siege. This essential lesson was ignored by rulers of second-and third-rank states, who constructed fortifications to project both military effectiveness and dynastic status but without incurring the huge and unsustainable additional costs of maintaining an effective field army. The result of such fortification projects-seen in case studies of the Farnese citadel at Piacenza, the Gonzaga at Casale-Monferrato and the dukes of Savoy at Pinerolo-was to undermine an earlier diplomacy based on a careful balancing of the major powers and their interests in Italy. Strategically placed citadels held by rulers without effective field armies presented both an enticement and a danger to the governments of France and Habsburg Spain. The result was a series of pre-emptive strikes which established garrisons of French or Spanish troops within these citadels, often to prevent the other major power doing the same thing, and a drastic curtailment of the freedom of the respective Italian princes.