Articles of the Treaty of Nemours (or Treaty of Saint-Maur) were agreed upon in writing and signed in Nemours on 7 July 1585 between the Queen Mother, Catherine de' Medici, acting for the King, and representatives of the House of Guise, including the Duke of Lorraine. Catherine hastened to Saint-Maur-des-Fossés, where on 13 July the treaty was signed between King Henry III of France and the leaders of the Catholic League, including Henri, duc de Guise. The king was pressured by members of the Catholic League to sign the accord which was recognized by contemporaries as a renewal of the old French Wars of Religion.
On 10 June 1584, the duc d'Anjou, François d'Alençon died. Since King Henry III was childless and likely to remain so, the legitimate successor to the throne of France was the king's distant cousin and chief of the Protestant party, Henri, king of Navarre. In the following spring, the Catholic League took control of many cities in northern France. In an attempt to gain control of the League, headed by members of the house of Guise, Henri III declared himself its chief, an act that forced him to break with Henri of Navarre.
The treaty cancelled all previous edicts, dismissed all Huguenots from official office and forced the King to capitulate to the demands of the Catholic League. Moreover, the duc de Guise was given Châlons as a security. As a result, the entire north-eastern half of France was directly controlled by the House of Guise. Moreover, the Guises were promised significant subsidies. Henri bluntly told Charles, Cardinal de Bourbon, that the overall accord would bring chaos and ruin to France. Nevertheless, the king signed the treaty in his attempts to outflank the Guise and become leader of the Catholic League himself. On 18 July he went in person to the Parlement of Paris to hold a lit de justice and force the Parlement to register the terms of the treaty, giving them the effect of law, as well as royal prerogative.