The Battle of Pavia took place in northern Italy on 24 February 1525. Its outcome profoundly affected the course of European international relations for the rest of the sixteenth century. King Francis I of France led his forces at the battle and was captured amidst the greatest slaughter of French nobles in war since Agincourt.  This book examines the early reigns of Francis, of his great rival Charles V, the Holy Roman Emperor, and a number of their contemporaries. It shows why warfare was such an important aspect of kingship in the period, and how it interacted with diplomacy. The book then looks at how Francis's siege of the city of Pavia turned into an open battle, why the king of France fought in person, and the main events of the encounter. It reviews Francis’s time as a prisoner in Spain and traces the complexity of international relations that provoked yet more war in the following decades, which drew in kingdoms as varied as Scotland, Tunisia, Hungary, and the Ottoman Empire. The book shows why the Battle of Pavia was one of the most important military encounters in the history of the European Renaissance.