Pope Julius II
League of Cambrai and Holy League

In addition to an active military policy, the new pope personally led troops into battle on at least two occasions, the first to expel Giovanni Bentivoglio from Bologna (17 August 1506 – 23 March 1507), which was achieved successfully with the assistance of the Duchy of Urbino. The second was an attempt to recover the Duchy of Ferrara for the Papal States (1 September 1510 – 29 June 1512). In 1508, Julius was fortuitously able to form the League of Cambrai with King Louis XII of France, Maximilian I, Holy Roman Emperor (proclaimed without coronation as emperor by Pope Julius II at Trent in 1508) and King Ferdinand II of Aragon. The League fought against the Republic of Venice. Among other things, Julius wanted possession of Venetian Romagna; Emperor Maximilian I wanted Friuli and Veneto; Louis XII wanted Cremona, and Ferdinand II desired the Apulian ports. This war was a conflict in what was collectively known as the " Italian Wars ". In the spring of 1509, the Republic of Venice was placed under an interdict by Julius, In May 1509 Julius sent troops to fight against the Venetians who had occupied parts of the Romagna, winning back the Papal States in the decisive Battle of Agnadello near Cremona.

During the War of the Holy League, alliances kept changing: in 1510 Venice and France switched places, and by 1513, Venice had joined France. The achievements of the League soon outstripped the primary intention of Julius. In one single battle, the Battle of Agnadello on 14 May 1509, the dominion of Venice in Italy was practically lost to the pope. Neither the King of France nor the Holy Roman Emperor was satisfied with merely effecting the purposes of the Pope; the latter found it necessary to enter into an arrangement with the Venetians to defend himself from those who immediately before had been his allies. The Venetians, on making humble submission, were absolved at the beginning of 1510, and shortly afterward France was placed under papal interdict.

Attempts to cause a rupture between France and England proved unsuccessful; on the other hand, at a synod convened by Louis at Tours in September 1510, the French bishops withdrew from papal obedience and resolved, with the Emperor's co-operation, to seek dethronement of the pope. With some courage Julius marched his army to Bologna and then against the French to Mirandola. In November 1511, a council met at Pisa, called by rebel cardinals with support from the French king and the Empire; they demanded the deposition of Julius II. He refused to shave, showing utter contempt for the hated French occupation. "per vendicarsi et diceva... anco fuora scazato el re Ludovico Franza d'Italia."

Whereupon Julius entered into another Holy League of 1511: in alliance with Ferdinand II of Aragon and the Venetians he conspired against the Gallican liberties. In a short time, both Henry VIII of England (1509–47), and Maximilian I joined the Holy League of 1511 against France. Ferdinand of Aragon now recognized Naples as a papal fief, invested in 1511, and therefore Julius II now regarded France as the main foreign power in the Italian peninsula hostile to Papal interests. Louis XII defeated the alliance at Battle of Ravenna on 11 April 1512. When a desperate battle felled over 20,000 men in a bloodbath the Pope commanded his protege, a newly released young Cardinal Medici to re-take Florence with a Spanish army. The rescue of the city on 1 September 1512 saved Rome from another invasion, ousting Piero Soderini, and returning the dynastic rule of the Medici. Julius had seemingly restored fortuna or control by exercising his manly vertu, just as Machiavelli wrote. This re-asserted a strong relation between Florence and Rome, a lasting legacy of Julius II. Yet Machiavelli and his methods would not outlast Julius' Papacy.

Julius hired Swiss mercenaries to fight against the French in Milan in May 1512, causing the French army to withdraw across the Alps into Savoy. The papacy gained control of Parma and Piacenza in central Italy. With the French out of Italy and Spain recognizing Naples as a papal fief, a Congress was held in Mantua by Julius II to declare the liberation of the peninsula. Nevertheless, although Julius had centralized and expanded the Papal States, he was far from realizing his dream of an independent Italian kingdom. Italy was not at peace either. The French were preparing new campaigns to reconquer Milan, and Julius II confessed to a Venetian ambassador a plan to invest his counselor Luigi d'Aragona with the Kingdom of Naples in order to end Spanish presence in the south. In fact, after the death of Julius, war would resume and the treaties of Noyon and Brussels in 1516 would again divide much of Italy between French and Spanish influence.
detectable_format:title, detectable_content:postscript