The French army was led by King Francis I of France, who laid siege to the city of Pavia (then part of the Duchy of Milan within the Holy Roman Empire) in October 1524 with 26,200 troops.

The historian Francesco Guicciardini summarised the clash as follows:[7] The King, fighting very gallantly, sustained the shock of the enemy, who, however, with their firearms obliged those about him to give way, till, the Swiss arriving and the cavalry charging them in flank, the Spaniards were repulsed.

But when the Viceroy came up he discovered himself to him, who, after kissing his hand with profound reverence, received him prisoner in the name of the Emperor.Francis was imprisoned in the nearby tower of Pizzighettone and later transferred to Spain, where Charles V was residing for his upcoming marriage with Isabella of Portugal.

Together they signed the Treaty of Madrid of 1526, by which Francis abandoned claims over the Imperial Duchy of Milan and ceded Burgundy to the House of Habsburg in exchange for his freedom.

While initially successful, the Imperial offensive lost valuable time during the Siege of Marseille and was forced to withdraw back to Italy by the arrival of Francis and the main French army at Avignon.

Nevertheless, Charles de Lannoy, who had concentrated some 16,000 men to resist the 33,000 French troops closing on Milan, decided that the city could not be defended and withdrew to Lodi on 26 October.

On 21 November, Francis attempted an assault on the city through two of the breaches but was beaten back with heavy casualties; hampered by rainy weather and a lack of gunpowder, the French decided to wait for the defenders to starve.

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

Confronted by the more numerous French and left without naval support by the arrival of a pro-Valois fleet commanded by Andrea Doria, the Spanish troops surrendered.

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

[citation needed] Pescara captured the French outpost at Sant'Angelo Lomellina, 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.

Medici was seriously wounded and withdrew to Piacenza to recuperate, forcing Francis to recall much of the Milan garrison to offset the departure of the Black Band; but the fighting had little overall effect.

Pescara, left in command of the Spanish forces after Lannoy had followed the retreating cavalry, formed his men up at the edge of the woods and sent messengers to Bourbon, Frundsberg, and Vasto requesting assistance.

[26] Frundsberg meanwhile mauled the heavily outnumbered Swiss infantry opposing him; Tiercelin and Flourance were unable to hold their troops together, and the French foot began to flee the field.

The French king fought on as his horse was killed under him by Cesare Hercolani, an Italian Condottiero;[27][28] surrounded by Spanish arquebusiers and German Landsknecht, he was taken prisoner and escorted from the field.

(" .... y en la misma batalla ficistes tanto que allegastes á la misma persona del dicho Rey, y fuistes en prenderle, juntamente con las otras personas que le prendieron ....")[35] Finally, in his autobiography, Charles V claimed that "the King was made prisoner by his principal captains", crediting the Duke of Bourbon, Charles de Lannoy, and the Marquis of Pescara.

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

[citation needed] In Rome Cardinal Ippolito de' Medici, who acted as Florentine emissary to Charles V in 1535, expressed support for the Emperor's victory by commissioning a rock crystal low relief in the manner of an Antique cameo, from the gem engraver Giovanni Bernardi.

[citation needed] An oil-on-panel Battle of Pavia, painted by an anonymous Flemish artist, depicts the military engagement between the armies of Charles V and Francis I.

[42] Although partially mutilated during the eighteenth and nineteenth centuries, when it was transformed into a farm, the Mirabello Castle, once the seat of the ducal captain of the park, still stands today a short distance from Vernavola and preserves inside some curious decorative elements (fireplaces, frescoes and windows) not yet adequately restored and studied, in French late Gothic style, added to the structure of the Sforza period during the first French domination of the Duchy of Milan (1500- 1513).

[43]In the nearby town of San Genesio ed Uniti in via Porta Pescarina there are some of the remains of the park gate where, in the night between 23 and 24 February 1525, the imperials made the three breaches that started the battle.