He would not however conduct the campaign with much enthusiasm, and after clamour at court he would be replaced by Anne de Joyeuse He playing a key role in the Day of the Barricades and Assassination of the Duke of Guise (1588).

Upon the assassination of Henri III in 1589, he would transfer his loyalties to the Protestant Navarre and would campaign for him in Burgundy, Maine and Brittany against the Duke of Mercœur.

[5] While staying at Blois in December the king met with Aumont, Rambouillet and d'Ornano in a secret council, at which they agreed that Guise would have to be killed.

[6] Having worked out the specifics of the plan, the king informed Guise of his intention to retreat to his château at La Noue for Christmas and his desire that the whole council meet prior to departing.

The Cardinal of Guise, and the Archbishop of Lyons who had remained in the chamber heard the commotion, and attempted to rush in to support their kinsmen and ally.

[10] Aumont was among the nobles who attended the heavily guarded funeral for the king in Compiègne as the civil war continued to rage.

[13] The same year he campaigned in Maine seeking to reverse the royal loss at the Battle of Craon, he captured Mayenne and would take Laval in 1594.