His disastrous defeat at the Battle of Pavia, where he was captured by the Imperial captain Charles de Lannoy and many of his chief nobles were killed, led to the end of the war.

Diplomatic manoeuvres to obtain his release included a French mission sent by his mother, Louise of Savoy, to the court of Suleiman the Magnificent that resulted in an Ottoman ultimatum to Charles.

[4] They were divided on the question of the Imperial succession; the Holy Roman Emperor, Maximilian I—intending for a Habsburg to succeed him—campaigned throughout 1518 on behalf of his grandson Charles I of Spain, while Francis I of France put himself forward as an alternate candidate.

[5] The Papacy and the Holy Roman Empire were forced to cooperate in dealing with the rising influence of Martin Luther, who found support among some Imperial nobles when he opened the way for them to assume authority over their local churches.

[6][7] At the same time, Francis was faced with Henry's able, efficient and intelligent chief advisor Cardinal Thomas Wolsey, the "power behind the throne" who interposed himself into the quarrels of the continent in an attempt to increase both England's influence and his own.

To divert Charles—and his army—from entering and possibly taking control of Italy, Francis sought to wage war on the emperor by proxy,[21] and made plans for simultaneous incursions into German and Spanish territory.

[22] The expedition was nominally led by the 18-year-old Navarrese king Henry d'Albret, whose kingdom had been invaded by Ferdinand II of Aragon in 1512, but the army was effectively commanded by André de Foix and funded and equipped by the French.

[22] The French plans proved to be flawed, as the intervention of Henry of Nassau drove back the Luxembourg offensive; and although de Foix was initially successful in seizing Pamplona, he was driven from Navarre after being defeated at the Battle of Esquiroz on 30 June 1521.

[6] Pope Leo X was unwilling to tolerate open defiance of his own authority, and considered the Emperor as a potential ally to support him against Luther, whose backers included Frederick of Saxony.

[26] Leo, needing the Imperial mandate for his campaign against what he viewed as a dangerous heresy, promised to assist in expelling the French from Lombardy,[27] leaving Francis with only the Republic of Venice for an ally.

Francis was confident that seizing the disputed lands would improve his own financial position sufficiently to continue the war and began to confiscate portions of them in Louise's name.

[46] Bourbon, angered by this treatment and increasingly isolated at court, sought redress by making overtures to Charles V.[46] The death of Doge Antonio Grimani brought Andrea Gritti, a veteran of the War of the League of Cambrai, to power in Venice.

The French, stretched thin by the Imperial attack, were unable to resist, and Suffolk soon advanced past the Somme, devastating the countryside in his wake and stopping only 80 kilometres (50 mi) from Paris.

Sweeping through most of the smaller towns unopposed, Bourbon entered the provincial capital of Aix-en-Provence on 9 August 1524, taking the title of Count of Provence and pledging his allegiance to Henry VIII in return for the latter's support against Francis.

The city was ridden with the plague, and so to avoid his troops becoming infected, on 26 October he withdrew to Lodi,[64][65] leaving Milan through one gate as the French vanguard under Salazzo entered through another.

At the urging of Bonnivet and against the advice of his other senior commanders, who favoured a more vigorous pursuit of the retreating Lannoy, the king's army then advanced on Pavia, where Antonio de Leyva remained with a sizable garrison.

[71] In early December, a Spanish force commanded by Hugo of Moncada landed near Genoa, intending to intervene in a conflict between pro-Valois and pro-Habsburg factions in the city.

[73] The French outpost at San Angelo was taken,[74] cutting the lines of communication between Pavia and Milan, while a separate column of landsknechts advanced on Belgiojoso and, despite being briefly pushed back by a raid led by Medici and Bonnivet, occupied the town.

[79][76] It was further weakened by the desertion of 2,000 Germans and the departure of nearly 5,000 Grisons Swiss mercenaries, who returned to their cantons to defend their own region following the capture of the town of Chiavenna by Milanese troops.

[87][72] Francis's ploy failed to achieve his aim of leading the Spaniards to abandon northern Italy,[63] as the Imperial commanders ultimately decided not to attack Albany but to concentrate on relieving Pavia.

[77] Lannoy attempted to intercept the expedition near Fiorenzuola, but suffered heavy casualties and was forced to return to Lodi by the intervention of the Black Bands of Giovanni de' Medici, which had just entered French service.

[92] The night following the Battle of Pavia, Francis gave Lannoy a letter to be delivered to his mother in Paris, in which he related what had befallen him: "To inform you of how the rest of my ill fortune is proceeding, all is lost to me save honour and life, which is safe."

The broken remnants of the French forces, aside from a small garrison left to hold the Castello Sforzesco in Milan, retreated across the Alps under the nominal command of Charles IV of Alençon, reaching Lyon by March 1525.

[96] Bourbon, meanwhile, plotted with Henry to invade and partition France,[97] and at the same time the Milanese chancellor, Girolamo Morone [it], proposed to d'Avalos that he lead the Italians against their oppressors, and seize the Neapolitan crown for himself.

[100] In December 1525 a second mission was sent, led by the Croatian nobleman John Frangipani, which managed to reach Constantinople with secret letters asking for the deliverance of Francis and an attack on the House of Habsburg.

Francis was convinced he would gain his freedom again if he obtained a personal audience with Charles, and pressed Lannoy, who had intended to transport the king to the Castel Nuovo in Naples, to send him to Spain instead.

[104] Francis was initially held at the castle at Tarragona, before being moved to Valencia and then to a nearby villa in Benisanó,[105] but Charles, urged to negotiate a settlement by Montmorency and Lannoy, who suggested that the Italians would soon prove unfaithful to their Imperial alliance, ordered the king brought to Madrid and imprisoned in the citadel there.

[111] By the beginning of 1526, Charles was faced with demands from Venice and the Pope to restore Francesco II Sforza to the throne of the Duchy of Milan, and had become anxious to achieve a settlement with the French before another war began.

[120] Clement VII became convinced that the Emperor's growing power was a threat to his own position in Italy, and Venetian and papal envoys went to Francis suggesting an alliance against Charles.

[124] France failed to regain any former possessions in Lombardy; the terms of the Peace that ended the Italian Wars gave Spain control of Milan, Naples, Sicily, Sardinia, Savoy, and Piedmont.