In 1636, Louis conspired with his cousin Gaston d'Orléans and the count of Montrésor with the intention to murder Cardinal Richelieu and depose the King, but the plot failed. The King's mother, Marie de' Medici, had tried as well on numerous occasions to remove the Cardinal as well as once trying to depose the King in favor of her younger son Gaston. For this she was placed under house arrest for the remainder of her life.
Louis's army was engaged by a royal French army under Gaspard de Coligny, Marshal Châtillon at Sedan, but Coligny was routed at the Battle of La Marfée outside of Sedan on 6 July 1641.[2] Of the King's 11,000 force, 600 were killed, 5500 were taken prisoner, while the Count of Soissons' forces suffered nominal losses. This was due to the late slow arrival of the King's forces through muddy roads and the surprise cavalry attack from their flank from behind a hill. The Count of Soissons, however, was killed after the battle by one officer whose identity was never ascertained, possibly in the employ of Cardinal Richelieu.[2] According to some sources, the Count died by accident while lifting the visor of his helmet with a loaded pistol, shooting himself in the head.[3]
Louis Henri de Bourbon, bâtard de Soissons,[4] Count of Noyers and of Dunois, Prince of Neuchâtel (August 1640 – 8 February 1703) illegitimate son of Louis and Élisabeth des Hayes. Line continues in the Dukes of Luynes family. Married Angelique Cunegonde de Montmorency-Luxembourg, daughter of François Henri de Montmorency.[4]