In the crisis over the excommunication of the queen of Navarre Saint-Sulpice relayed information of a Spanish plot against her to the French court thus aiding in its neutralisation.

During the fourth war of religion Saint-Sulpice engaged in internal diplomatic efforts and was tasked with the arrest of the governor of Languedoc the baron de Damville.

[15] Only Antoine would undertake a thorough education at the institution however, while Henri and Armand undertook the 'education of a gentleman' (music and martial pursuits - their horse riding taught to them by the tutor of the duc d'Anjou).

[1] In the evening of 14 November 1559, while peace negotiations with España were ongoing, Catherine and the duc de Guise implored Henri not to surrender French Piemonte as part of any treaty.

[24] On 15 November, Henri summoned his council and announced to the assembled grandees that he had resolved on making peace with the Spanish king Felipe even if this meant the returning of the majority of the French conquests of the Italian Wars including Corse, Piemonte and parts of Luxembourg.

[5] While talks had been stalling at Cercamp, Saint-Sulpice's arrival so dramatically altered the position of the French delegates, that the Spanish wondered whether it was some sort of ploy.

On 18 July word arrived of the death of Henri II, with hope quickly spreading that the French withdrawal might be reversed, however it was confirmed by the new administration.

[35] Tied up in court, his brother, the abbot of Marcilhac, and his wife oversaw the recruitment of men for his compagnie, a process they began before the captaincy had been bestowed on Saint-Sulpice formally.

[60] Recently established in España, Saint-Sulpice corresponded with the duc de Guise who was jointly leading the royal armies in France in September 1562.

[67] Chantonnay, the Spanish ambassador, held suspicions as to the religious orthodoxy of the French king's brother's tutor François de Carnavalet and feared that he might imbue his 'religious deviancy' in the teachings of the young prince.

[76] Saint-Sulpice and the French court reacted with irritation to the Spanish unease at the activities of the Protestant prince de Condé and return of the seigneur d'Andelot to his office of colonel-general of the infantry.

[80] Monluc further envisioned Felipe seizing control of Béarn from the queen of Navarre thereby uniting the destruction of Protestant power with the enlargement of the Spanish realm.

[96] The king afforded him benefit for his role in España by ordering a six-month suspension in any litigation in France concerning him on the grounds that of his Spanish residence.

[96] Saint-Sulpice endeavoured to gain an understanding of grand Spanish plans at sea in late 1564, but reported to the French court in June and August that he struggled to obtain clear answers from Felipe.

[97] When the French court reached Dauphiné during its royal tour, Catherine reminded the queen of España, her daughter of her desire for a meeting to come to pass between the sovereigns.

[98] Saint-Sulpice also protested against the activities of the queen of Navarre's uncle the bishop of Comminges, asking Élisabeth to weigh upon her husband 'not to employ such shady characters'.

[106] Alba informed Saint-Sulpice in February that it was foolish to imagine that France could emerge from its current crisis and the evils that plagued the kingdom without Spanish support.

Saint-Sulpice attempted to have the prohibition on attendance limited to the queen of Navarre, Condé, Coligny and the cardinal de Châtillon, however it was made clear to him no Protestants were acceptable.

The declaration offered vague support in favour of Catholic unity, though Alba opined to Felipe that as soon as the Protestants arrived at Bayonne, Catherine's position would reverse.

[5] Back in España, Saint-Sulpice was faced with difference of opinion between the French and Spanish crowns over the matter of princely marriages and a league against the Osmanlı İmparatorluğu.

[118] Saint-Sulpice still participated in military service, even during the 1560s and saw combat during the first months of the second war of religion at the royalist victory of the battle of Saint-Denis in November 1567 where he was wounded and his former protector constable Montmorency killed.

[122] In addition to his own relatives, Saint-Sulpice was also able to secure promise of favour from the duc de Longueville in return for installing a client of his named La Baratte into Alençon's household as a valet.

[126] Saint-Sulpice was among the grand lords assembled to hear the articles of peace that had been negotiated by the king to bring the third war of religion to a close in August 1570.

[136] Saint-Sulpice wrote with considerable excitement to his wife during the progress of the siege as to his contact with the duc d'Anjou 'Monsieur [Anjou] does me much honour and speaks to me privately more than I could have hoped or thought for... be assured that I do not forget my friends during these moments'.

[4] The baron was briefed by the king in mid January that there existed in Poitou and Saintonge evildoers who were bringing both the Catholic and Protestant nobility into opposition to the crown in the name of the 'common good'.

[145] Thus briefed, Saint-Sulpice proved critical in preventing an alliance between the 'gentleman of La Rochelle, Poitou and Saintonge' with the rebellious Protestants of Languedoc who were entering a state of rebellion in January 1574.

[150] When the king entered his cabinet for the day the following men were to remain present in the chamber: princes, officers related to the affairs at hand, the four sécretaires d'État, the bishops of Orléans, Limoges and Valence, the future archbishop of Toulouse, Bellièvre, Pibrac, and Saint-Sulpice, alongside a couple of others.

Greatly aggrieved by these refusals, Zweibrücken had the French diplomats who were with him arrested in August and made them bare witness to his triumphant entry into Heidelberg, accompanied by all the money and jewels he had already received from France.

The sécretaire d'État Villeroy would then be dispatched in September with new instructions, and a treaty was negotiated successfully with the Protestant rebels to bring the war to a close.

[178] During negotiations Saint-Sulpice, Pibrac, Foix and the cardinal de Bourbon rejected the 36 article cahiers grievances submitted by the Protestant church of Languedoc on the grounds most of the demands were contrary to the previous peace edict.