Enguerran VII, the last of Coucy Lord, died without male heir. His legacy is for his daughters that his legacy will be composed of the land of Coucy, Marle, La Fère, Origny, the County of Soissons, Ham, Pinon, Montcornet, the vinage of Laon, an hotel in Paris ... Plus a pension of 1,800 pounds on the treasury of the king. In her first marriage, with Ysabeau of England, he had two daughters: Mary, wife of the Duke of Bar, who died in 1398 in Treviso, returning from Bithynia, who had entrusted the care of his wife and children at Louis of Orléans, and Philippa, married to Robert of Vere, who had inherited the English and Scottish possessions of his father. From his second marriage, was born Ysabeau. Taking advantage of its position vis-à-vis Mary, the Duke of Orleans endeavors to collect inheritance thereof. And on Nov. 15, 1400, no longer hold, Marie sells the properties of Coucy, Marle and La Fère, for 400,000 pounds to the latter. She died in 1405 had received only 90,000 pounds.

In order to avoid liability on the part of Ysabeau, younger sister of Mary, the Duke of Orleans gets Charles VI, his brother, that the property should be erected for him in peerage. The letters patent to be issued on December 21 14OO, they include Coucy, Folembray, St Aubin, La Fère, St Lambert des Eaux, Acy and Gercy and their dependencies. Ysabeau takes action against Louis of Orleans, and Mary, but justice delayed procedures.

In 1402, louis of Orléans retired to Coucy, because of the support enjoyed by the King to the Duke of Burgundy, its enemy, which was to be set aside for a time of power. But the latter died in 1404, then a rapprochement between the two factions that share power: Louis of Orléans receives administration in the South of France, Jean of Burgundy, the north. As a result, a marriage between Charles, Count of Angoulême, son of Louis of Orléans, with Isabelle of France, widow of the king of England. But on Nov. 23, 1407 assassination of Louis of Orléans by the Burgundians concludes this agreement.

On the other hand, on Aug. 11, 1408, Parliament gave its judgement on the legacy of Enguerran VII, forcing the Duke of Orleans to pay 200,000 pounds in compensation to Ysabeau of the Land of Coucy where it belongs now fully .

Then, in 1409, the Duke of Burgundy apologise to the king for his crime and then marry his son Jean, Count of Nevers, Ysabeau of Coucy. This marriage attended Charles of Orléans was followed in 1410 with his own daughter of the Count of Armagnac (Isabelle of France having passed away shortly before) and an alliance that puts the party of Armagnac alongside the Burgundians.

The following year began a war between Burgundians and Armagnacs. Charles of Orléans puts cities in Picardy he owns, in a state of defence. The Duke of Burgundy sends Valeran of Luxembourg, Count of St Pol, the head of 60,000 men put the seat in front of Coucy. The city - commissioned by Enguerran of Fontaines - surrender without resistance, to the cry of "Long life to Burgundy." But the castle, at the hands of Robert of Esnes, governor of the place that refuses to surrender, he resists. The Master Odon’s Gate defending the lower court is unsuccessfully undermined and one of the corner towers collapses in part on the knights besieging, came to inspect the work. Finally, at the end of ammunition, and receiving no relief, Robert of Esnes capitulated. He receives 8,000 ecu and freedom to withdraw him and the garrison with weapons and luggage for Crèvecoeur or Cateau-Cambresis, places still in the hands of Charles of Orléans. For this act, the Count of St Pol Constable was appointed. Coucy remains in the hands of Burgundians until 1412, when peace was signed at Auxerre and Coucy get back to the Duke of Orleans.

But the offensive resumed in 1413, at the initiative of the Duke of Orleans, dissatisfied with the result of the gathering of the Etats Généraux, unable to control the situation. Jean of Bourgogne is defeated in Arras Charles of Orléans, but fails to take advantage of his victory a long time since he was wounded in Agincourt (1415) and taken captive in England, which takes advantage Jean of Bourgogne, which continues the fight against vassals of Orleans.

In February 1419, the lords of Maucourt, Bournonville, Humeroeuille and other Burgundy supporters were trapped in Coucy, in the custody of Pierre of Xantrailles, when with the complicity of two servants and a maid, they have free himself by assassinating the governor of the castle garrison and then seizing the castle - without La Hire, who commanded the city, could prevent them from doing so. Forced to withdraw because Jean, Count of Luxembourg coming to the rescue of Burgundy, he left the place, but returned in 1420, accompanied by Pothon of Xantrailles, brother of the former, and resumed Coucy. Thereafter, Jean said "Fearless" was murdered in Montereau.

Coucy is again taken over by the English, this time under the command of the Duke of Suffolk they hold the place for 7 years. When in 1440 Charles of Orléans is finally released, thanks to the request of Philip the Good, the son of Jean of Bourgogne, Jean of Luxembourg had died, the officer commanding Coucy in his name for English, withdrew from the place through finance.

To alleviate the misery that was rampant, a salt granary was created in 1422. The following years little interest Coucy, which remains in the shadow of the political scene: CharIes VII died in 1461. Two years later, Louis of Orléans born. He’ll get engaged, in 1465, to Jeanne of France, the daughter of Louis XI, while Charles of Orléans was extinguished on January 4, 1465. Then, Louis XI in turn, died on August 30, 1483. Anne of Beaujeu, his daughter, then takes the regency of Charles VIII - aged 13 -. But the princes unhappy to see the power their escape rebel; at their head, Louis of Orléans and the Duke of Brittany, with the allied Archduke Maximilian, King of the Romans, who tried in vain to invade Artois at the head of 12,000 men, but that was rejected by the Maréchal Esguerdes, commander of the royal army. The latter takes Coucy after 8 days of siege in order to ensure that Louis of Orléans can use them against the royal authority. The revolt was suppressed permanently on July 27, 1488, the day of the Battle of St Aubin du Comte, during which Louis of Orléans was taken prisoner.

He was released in 1491, and after he reconciled with the king, the government receives in Normandy, comes into possession of all their land including Coucy where he sends his chamberlain Georges of Sully as governor. It was then that Charles VIII died at Amboise in 1498 and that Louis of Orléans is recognized king by the name of Louis XII.