The war between France and Spain began in 1521, after the Hapsburg Charles I, who was already King of Spain, became Emperor of the Holy Roman Empire with the name Charles V. The main object of the conflict was once again Italy where, after the Treaty of Noyon in 1516, France had possession of Milan and Spain controlled Naples. The first years of the war went badly for the French who were subjected to heavy defeats and who lost the Duchy of Milan. At the end of September 1524, Francis I entered Italy at the head of a powerful army, having decided to finish the war once and for all. The Spanish and Imperial troops abandoned Milan, leaving a strong garrison in the town of Pavia and pulled back beyond the River Adda. The defense of the town was left to the able and resolute Antonio de Leyva. At the end of October, the French put Pavia under siege. During the course of the next three months, the town resisted all assaults while the Spanish and Imperial troops had put together a strong army with the troops arriving from Germany.