He aligned himself with the Catholic Ligue that rose up in opposition to the generous Peace of Monsieur and fought in the sixth war of religion that resulted, serving at the sieges of La Charité-sur-Loire and Issoire.

Mayenne was granted full command of a royal army during the seventh war of religion in 1580, besieging the Protestant stronghold of La Mure successfully, and clearing several holdout towns after the peace.

Forced to make concessions he agreed to establish an Edict of Union, with religiousity overriding Salic Law in determining succession, and to appoint Mayenne to lead one of his principal armies for a war against heresy.

In February 1589, Mayenne accepted appointment by the Seize regime in Paris as lieutenant-general of the kingdom, he visited many ligueur aligned cities in the north east, reorganising their administrations as best he could on lines that suited him.

[17] Despite the prestige of this position, Henri III allowed it to have little real authority during his reign, though he permitted Mayenne to share his table alongside the Gentilhomme de la Chambre.

[41] In the confusing combats that characterised the fifth war of religion, Mayenne led an army in late 1575 facing off against a Protestant mercenary force under Casimir von Pfalz-Simmern that had invaded the kingdom.

[42] Encamped at Vitry-le-François, Mayenne's 10,000 men were ravaged by hunger and lack of pay and were able to do little more than shadow Casimir as he moved to Dijon on 31 January 1576, and then Moulins on 4 March, where he united forces with the politique brother of Henri, Alençon.

Mayenne moved off without Alençon with his own force, and on 18 August captured the town of Brouage on the Atlantic coast, with the assistance of the seigneur de Lanssac, securing a considerable supply of salt.

He and Mayenne met with Casimir to discuss a plan to seize Strasbourg, however ultimately nothing would come of this inter-confessional moment, and the Lorraine family returned to their reputation for crushing heresy.

[55][56] With the Treaty of Fleix concluding the conflict by the end of the year, Mayenne was entrusted with ensuring that it was enforced, and obtaining the submission of the holdout towns of Livron and Gap, a task in which he was successful.

[61] In his capacity as governor of Bourgogne, Mayenne marshalled his clientèle in support of the ligue, while his brother Guise mobilised Champagne, and his first cousins Aumale and Elbeuf prepared for rebellion in their strongholds of Picardie and Normandie respectively.

While Guise was alive he was tenuously able to hold the two components together in a united purpose, however after his assassination in 1588, Mayenne struggled to replicate this unity, and the ligue movement began to splinter.

[64] With open hostilities declared on the crown by Guise's armed entry into Châlons on 21 March, Mayenne quickly moved to secure the major cities of his governate.

Henri was prevented from coming down with a firmer hand on the plotters by the death of Marie de Lorraine in England, who provided the ligueurs a strong martyr that invigorated their cause, with churches throughout Paris mourning her.

[74] Back on campaign, he entered Guyenne in mid 1587, capturing the Protestant stronghold of Monségur, however his advance was increasingly slow and he was unable to prevent Condé and Navarre from uniting forces.

[75] Observing his foundering, Catherine de' Medici urged her son to send reinforcements to bolster his campaign, which Henri assented to in August, dispatching forces both to Mayenne and his favourite Épernon who was fighting in Valence.

The Third Estate resultingly promised a paltry 120,000 écus to keep the kingdoms finances afloat, however in a further twist of the knife these were not to go to the king but instead directly delivered to the crown's armies under the authority of Mayenne and Nevers.

[15] On 12 February, Mayenne, alongside his cousin Aumale, and ally the duke of Nemours presented themselves before the church of Saint-Jean-de-Grève in Paris where they were hailed by ecstatic crowds with cries of 'Long live the Catholic princes!

Few were convinced by this eleventh hour change, and Mayenne himself visited Rouen on 4 March, to install a ligueur provincial council, with the more reliable Villars, Meilleraye and his brother Pierrecourt at its head.

[111] During December 1592, Mayenne wrote to the ligueur administration of Troyes, warning them about the rumours of Henri's plans to convert to Catholicism, reminding them that he would still be excommunicated and thus unworthy to rule France, as such not invalidating their rebellion.

[113] He followed this up with the appointment of the baron de Rosne and Saint-Paul in overall authority as lieutenant-general of Champagne, giving them the effective powers of governor due to the imprisonment of the young duke of Guise.

[122] In total there were 12 provincial ligueur councils across France, Agen, Amiens, Bourges, Dijon, Le Mans, Lyon, Nantes, Poitiers, Riom, Rouen, Toulouse and Troyes.

[135] Mayenne looked desperately for outside assistance, receiving a welcome coup when forces under Claude de La Châtre ligueur governor in Berry arrived to bolster the garrison.

[153] Mayenne alone was unable to relieve the siege, and as such the Seize turned to Felipe for support, securing agreement for military aid in August through the threat that Paris' fall would entail a Protestant France.

[159] Other leaders of the Seize such as Bussy-Leclerc and Crucé were expelled from the city, and he took control of the Bastille[146][154][160] Normandie had become the main theatre in which the conflict between Henri and the ligue was fought, and the two sides again met in early 1592 during the siege of Rouen.

Parma hoped to go on to crush the main royal army which was in retreat to Pont de l'Arche, but Mayenne insisted they clear the royalist controlled forts in the vicinity of Rouen.

[165] Guillaume du Vair and Le Maistre, two moderate ligueur Parlementaires, who had walked out of the estates after the Spanish proposal engineered a decree the Parlement declaring that no foreign prince could become king of France, earning rebukes from both the Seize and Mayenne.

[173] The war was becoming increasingly dire for Mayenne and the ligue, he reacted apoplectically when word reached the capital that nearby Meaux had surrendered to Henri, allegedly tearing the letter bearing the news apart with his teeth.

[95] In the Edict of Folembray of September 1595 that re-secured his loyalty he was granted three surety towns (Chalon, Seurre and Soissons) for a period of 6 years, the governorship of the Île de France (but without control over Paris, Melun or Saint-Denis) and a bribe of 900,000 écus.

[192] His return to the royalist camp, came in great part due to the fact that the ligueur cause was increasingly a lost one, and if he wished to preserve his titles and landed influence, some form of accommodation was the only way to facilitate this.