Military action
Although the Italian Wars (1494–1559) came to dominate the reign of Francis I, which he constantly participated in at the forefront as le Roi-Chevalier, the wars were not the sole focus of his policies. He merely continued the wars that he succeeded from his predecessors and that his heir and successor on the throne, Henry II of France, would inherit after Francis's death. Indeed, the Italian Wars had begun when Milan sent a plea to King Charles VIII of France for protection against the aggressive actions of the King of Naples.
Much of the military activity of Francis's reign was focused on his sworn enemy, the Holy Roman Emperor Charles V. Francis and Charles maintained an intense personal rivalry. In addition to the Holy Roman Empire, Charles personally ruled Spain, Austria, and a number of smaller possessions neighbouring France, and was thus a constant threat to Francis I's kingdom.
Militarily and diplomatically, the reign of Francis I was a mixed bag of success and failure. Francis had tried and failed to become Holy Roman Emperor at the Imperial election of 1519, primarily due to his adversary Charles having threatened the electors with violence. There were also temporary victories, such as the portion of the Italian Wars called the War of the League of Cambrai (1508–1516), especially the final stage of the war, which history refers to simply as "Francis's First Italian War" (1515–1516). Francis routed the combined forces of the Papal States and the Old Swiss Confederacy at Marignano on 13–15 September 1515. This grand victory allowed Francis to capture the Italian city-state of Milan; however, in November 1521, during the Four Years' War, Francis was forced to abandon Milan in the face of the advancing Imperial forces of the Holy Roman Empire and open revolt within the duchy.
Francis I attempted to arrange an alliance with Henry VIII at the famous meeting at the Field of Cloth of Gold on 7 June 1520, but despite a lavish fortnight of diplomacy they failed to reach an agreement. Francis and Henry VIII both shared the dreams of power and chivalric glory; however their relationship featured intense personal and dynastic rivalry. Francis was driven by his intense eagerness to retake Milan, despite the strong opposition of other powers. Henry VIII was likewise determined to recapture northern France, which Francis could not allow.
However, the situation was grave; Francis had to face not only the whole might of Western Europe, but also internal hostility in the form of Charles III de Bourbon, a capable commander who fought alongside Francis as his constable at the great battle of Marignano, but defected to Charles V after his conflict with Francis's mother over inheritance of Bourbon estates. Despite all this, the Kingdom of France still held the balance of power in its favour. Nevertheless, the defeat suffered from the cataclysmic battle of Pavia on 24 February 1525, during part of the continuing Italian Wars known as the Four Years' War upheaved the political ground of Europe. He was actually taken prisoner: Cesare Hercolani injured his horse, and Francis himself was subsequently captured by Charles de Lannoy. Some claim he was captured by Diego Dávila, Alonso Pita da Veiga, and Juan de Urbieta, from Guipúzcoa. For this reason, Hercolani was named "Victor of the battle of Pavia". Zuppa alla Pavese was supposedly invented on the spot to feed the captive king after the battle.
Francis was held captive in Madrid. In a letter to his mother, he wrote, "Of all things, nothing remains to me but honour and life, which is safe." This line has come down in history famously as "All is lost save honour." Francis was compelled to make major concessions to Charles in the Treaty of Madrid (1526), signed on 14 January, before he was freed on 17 March. An ultimatum from Ottoman Sultan Suleiman to Charles additionally played a role in his release. Francis was forced to surrender any claims to Naples and Milan in Italy. He was forced to recognise the independence of the Duchy of Burgundy, which had been part of France since the death of Charles the Bold in 1477. And finally, Francis was betrothed to Charles' sister Eleanor. Francis returned to France in exchange for his two sons, Francis and Henry, Duke of Orléans, the future Henry II of France, but once he was free he revoked the forced concessions as his agreement with Charles was made under duress. He also proclaimed that the agreement was void because his sons were taken hostage with the implication that his word alone could not be trusted. Thus he firmly repudiated it. A renewed alliance with England enabled Francis to repudiate the treaty of Madrid.
Francis persevered in his rivalry against Charles and his intent to control Italy. By the mid-1520s, Pope Clement VII wished to liberate Italy from foreign domination, especially that of Charles, so he allied with Venice to form the League of Cognac. Francis joined the League in May 1526, in the War of the League of Cognac of 1526–30. Francis's allies proved weak, and the war was ended by the Treaty of Cambrai (1529; "the Peace of the Ladies", negotiated by Francis's mother and Charles' aunt). The two princes were released, and Francis married Eleanor.
On 24 July 1534, Francis, inspired by the Spanish tercios and the Roman legions, issued an edict to form seven infantry Légions of 6,000 troops each, of which 12,000 of the 42,000 were to be arquebusiers, testifying to the growing importance of gunpowder. The force was a national standing army, where any soldier could be promoted on the basis of vacancies, was paid wages by grade and granted exemptions from the taille and other taxes up to 20 sous, a heavy burden on the state budget.
After the League of Cognac failed, Francis concluded a secret alliance with Philip I, Landgrave of Hesse on 27 January 1534. This was directed against Charles on the pretext of assisting the Duke of Württemberg to regain his traditional seat, from which Charles had removed him in 1519. Francis also obtained the help of the Ottoman Empire and after the death of Francesco II Sforza, ruler of Milan, renewed the contest in Italy in the Italian War of 1536–1538. This round of fighting, which had little result, was ended by the Truce of Nice. The agreement collapsed, however, which led to Francis's final attempt on Italy in the Italian War of 1542–1546. Francis I managed to hold off the forces of Charles and Henry VIII, with Charles being forced to sign the Treaty of Crépy because of his financial difficulties and conflicts with the Schmalkaldic League.