Son of the Charles I de Cossé and Charlotte d'Esquetot, Brissac was born into a family with a strong military reputation, both his father and uncle being French Marshals.

As a second son Brissac was not initially intended to assume the titles of his father, but his brother Timoléon de Cossé was killed during a siege in 1569.

Brissac was intimately involved in the French response to the Portuguese succession crisis of 1580, being selected by Catherine de Medici the queen's mother as one of the two military commanders for the expedition.

They were met with disaster at the Battle of Vila Franca do Campo, Strozzi was killed and Brissac took responsibility for extracting the ships that could be saved from the superior enemy.

Catherine desired for him to lead another expedition but Henry overruled her, and Brissac looked to the duke of Guise for purpose, becoming involved in the abortive plans for an invasion of England.

The ligue resolved to make war on the king to get him to revise his policy, and Brissac campaigned in Normandy but was bested by Épernon at the siege of Gien.

The king was compelled by the terms of the peace to make war on Protestantism, and in the subsequent campaign, the Protestant Condé seized Angers from Brissac.

In May 1588 tensions between the ligue and their nominal ally Henry overflowed and Paris rioted against the king's attempt to introduce troops to the capital.

A regency commission was established to examine the various claims, with the Spanish king Philip II pushing his candidacy, to unite the Iberian Peninsula.

Catherine and Henry agreed to organise an expedition in support of the conde de Vimioso to capture the Açores, which Spain had not yet seized.

[9] After some negotiations, Catherine and Henry decided in favour of the expedition, on 3 May 1582, Strozzi was ordered to make for Madeira, and use it as a springboard to capture the Azores, then to head to Brasil.

[12] Catherine now turned to Brissac to lead another expedition to the Açores himself, but Henry intervened, asking her to leave the choice to Admiral Joyeuse, his favourite.

[16] In September 1584, the Catholic League, which had been dormant since 1576, was refounded by the Lorraine family to oppose the succession of the Protestant Navarre, distant cousin to the king, to the throne.

Soon the governor of Anjou Bouchagae, his brother the royal favourite Joyeuse and La Châtre came to the relief of Angers, driving Condé's forces from the city.

Present in the city when Henry introduced his troops, Brissac was tasked by Guise with investigating the reason barricades had been thrown up by the people of Paris.

He engaged in a rousing speech in a house of a prominent ligueur to a group of militia officers urging them to fight for their liberty and the Catholic faith.

Brissac for his part drove onto the Île de la Cité, pushing back the king's Swiss guard before him, all the way to the Pont Notre Dame.

Guise was delighted to be offered the role of broker, and calmed the population, allowing for the remaining royal forces to be extricated from the city.

Fearing he was to be captured by the ligueurs he slipped out the capital quietly, leaving it in the hands of the ligue who established a radical administration known as the Seize.

When word came that the duke of Savoie had invaded Saluzzo, royalist delegates were initially able to take charge of the Second Estate in a patriotic fervour and lead them to advocate a war with Spain.

[44] The leader of the Third Estate, La Chapelle-Marteau, who had been made prévôt des marchands of Paris by the ligue after the Day of the Barricades was also arrested.

The non native ligueur troops under Brissac were asked to depart from the suburbs, as was the royalist governor La Rochepot and his forces.

Brissac returned quickly, bringing troops into the city proper while barricades were thrown up again and the gates secured by the ligueurs.

Brissac raised peasant levies in Normandy in to relieve the ligueur town of Falaise which was being besieged by the duke of Montpensier.

Brissac who had watched the slaughter from a nearby hill withdrew with his cavalry, Longchamp and Beaulieu had also betrayed the Gautier and abandoned them in their flight.

Brissac departed the city in mid-March for two days, and on his return, plead with the Cardinal for forgiveness for speaking with heretics, which was promptly granted.

[70] On 22 March his forces approached the capital from three directions, Brissac and the prévôt des marchands Pierre Lhullier ensured that two gates were open and the chain on the Seine lifted by 04:00.

The remaining diehard ligueurs in the city, Crucé and Hamilton, vainly attempted to rally the population against his entry, but they found little interest.

[68] The Spanish garrison filed out of the city shortly thereafter, Henry allowing their captain Feria to have his troops depart with full military honours.

[72][70] Betraying the capital offered Brissac both personal advantage, and also avoided the consequences of a forceful reduction of the key city.