Italian campaign of 1524–1525

French expeditions

In early December, a Spanish force under Hugo of Moncada landed near Genoa to intervene in a conflict between pro-Valois and pro-Habsburg factions. Francis sent a larger force under the Marquis of Saluzzo, which confronted the Spanish; with the arrival of a pro-Valois fleet under Andrea Doria, the Spanish surrendered. Francis then secretly agreed with Pope Clement VII to assist in conquering Naples in exchange for the Pope's neutrality.

Against his commanders' advice, Francis detached troops under the Duke of Albany to aid the Pope. Lannoy tried to intercept this force near Fiorenzuola but was repulsed by the Black Bands of Giovanni de' Medici, which had just entered French service. Medici returned to Pavia with supplies, but the French position weakened when nearly 5,000 Grisons Swiss mercenaries left to defend their cantons.

Lannoy's offensive

In January 1525, Lannoy received 15,000 fresh landsknechts under Georg Frundsberg and renewed the offensive. D'Avalos captured the French outpost at Sant'Angelo Lomellina, cutting communications between Pavia and Milan, while landsknechts occupied Belgiojoso after a brief raid by Medici and Bonnivet. By 2 February, Lannoy was a few miles from Pavia. Francis had encamped most of his forces in the walled park of Mirabello, placing them between the garrison and the relief army.

Skirmishing continued through February. Medici was seriously wounded and withdrew to Piacenza, forcing Francis to recall troops from Milan. On 21 February, low on supplies and mistakenly believing the French were more numerous, Imperial commanders decided to attack Mirabello Castle to save face and ensure a safe withdrawal.

Battle of Pavia

On 24 February 1525, Imperial engineers breached the walls of Mirabello, allowing Lannoy's forces to enter the park, while Leyva sortied from Pavia with the garrison. In the four-hour battle, the French heavy cavalry advanced rapidly, masking their own artillery, and were surrounded and cut apart by landsknechts and Spanish arquebusiers. The Swiss and French infantry were routed. French casualties were massive, losing most of the army.

Bonnivet, Jacques de la Palice, La Trémoille, and Richard de la Pole were killed; Anne de Montmorency, Robert de la Marck, and Francis himself were taken prisoner. That night, Francis wrote to his mother that all was lost save honour and life. He later learned that the Duke of Albany had lost most of his army to attrition and desertion without reaching Naples. The broken French remnants, aside from a small garrison in Milan's Castel Sforzesco, retreated across the Alps under Charles IV of Alençon, reaching Lyon by March.

Aftermath

After Pavia, the fate of Francis and France became the subject of diplomatic maneuvering. Charles V, lacking funds, forwent a marriage to the House of Tudor and sought instead to marry Isabella of Portugal for her dowry. Bourbon plotted with Henry VIII to invade and partition France, while encouraging d'Avalos to seize Naples and declare himself King of Italy.

Louise of Savoy, regent in France, gathered troops and funds to defend against an expected English invasion of Artois. Francis, convinced he could regain freedom by a personal audience with Charles, pressed d'Avalos and Lannoy to send him to Spain instead of Naples. Concerned by Bourbon's scheming, they agreed, and Francis arrived in Barcelona on 12 June.

Did You Know?

• The French had been forced to abandon Lombardy after their defeat at the Battle of Bicocca in 1522.
• Charles de Lannoy launched an invasion of Provence under d'Avalos and Bourbon, but it was forced to withdraw after the Siege of Marseille.