The duc de Châtellerault participated in the French 1515 campaign into Italy to reconquer territories for France as part of the vanguard of the army.
[3] Gilbert de Bourbon fought in the Italian Wars of Charles VIII, and briefly served as the king's viceroy and grand justicier in newly conquered Naples.
He was succeeded by his cousin and heir, the comte d'Angoulême who took the regnal name François I (alternatively rendered Francis I).
[10] Six days after the burial of Louis XII, king François made for Reims, so that he might be crowned and anointed in the holy oil.
[14] After some prayers and readings, François, preceded by the princes du sang, gave thanks at the altar to the Virgin Mary and god for the gifts they had given him.
[15] Around midnight, king François took his matins early, alongside only the close princes du sang.
[16] This group of pairs and the king awaited the arrival of the abbot of Saint-Remi, who brought the Holy Ampulla (the vial containing the anointing oil).
[23] To support a campaign, François hired around 20,000 landsknechts (German pikemen) as infantry, as he was unable to enjoy the services of the Swiss.
Though this league appeared mighty on paper, in practice, the duke of Milan would primarily have to rely on the Swiss for support, though the Pope did send a force of 1,500 horse north into Piedmont under the command of the condotierri (a type of contract mercenary) Prospero Colonna.
The king would have 3,000 hommes d'armes (men-at-arms) of the compagnies d'ordonnance (the heavy cavalry units that formed the core of the royal army), in addition to noble pensioners.
Ten thousand infantry were dispatched to the Susa pass (the regular means of French egress into Italy), while Colonna took the other 8,000 to Saluzzo.
Novara, abandoned by the Swiss, was quickly captured by the French infantry with 700 lances (a heavy cavalry unit).
Some cantons were favourable to a settlement by which they would abandon Milan in return for a large sum of money, and the compensation of the Milanese duke by the receipt of the duché de Nemours (a fief in France).
[26] This force marched with haste in silence, but their stealth was compromised by the large cloud of dust raised by their numbers.
Bourbon had command of the vanguard (of which Châtellerault was a member), which was to be found at San Guiliano near Milan, which contained the artillery lined behind a trench with a row of shooters.
The battle (core of the army) was with the king a kilometre south around Santa Brigida with another 9,000 landsknechts and the cream of the gendarmerie under the command of François.
Châtellerault's brother Bourbon and the maréchal de La Palice led the hommes d'armes of the vanguard into the Swiss, but were rebuffed by the pikeman and forced to retreat back to their foot soldiers.
[27] The king then rallied several thousand of the landsknechts and some hommes d'armes and was able to prevent another group of Swiss from taking the artillery, forcing them to retreat back across the ditch they had crossed.
[29] François took advantage of the interlude to spin off a letter to Alviano, imploring his Venetian ally to hurry and join with them.
[31] The king was in great personal danger at this time, receiving several pike wounds, while many of his nobles fled the field towards Marignano.
In his letters to the cities of France he moderated the number of Swiss casualties, lowering the total to fifteen or sixteen thousand.
[28] The bodies of the great nobles like Châtellerault killed at Marignano were embalmed and then put in lead lined coffins so that they might be brought back to France for burial.
[30] Meanwhile, Châtellerault's brother, the duc de Bourbon, would give the order for the burial of other soldiers on the site of the battle.
[31] After his death, control of the lands of Châtellerault would fall to his elder brother, the duc de Bourbon.