Louis of France (1368-1407), son of Charles V and brother of Charles VI, purchased the counties of Blois and Dunois from the elderly Count Guy II of Chastillon in 1391 and took possession of them after the Count’s death in 1397. At first Duke of Touraine, he exchanged this appanage in 1394 in favor of the Duchy of Orléans which was far more richer.
His influence over Charles VI ,who went mad in 1394, and his policy of purchasing land brought him into rivalry with the Dukes of Burgundy, Philip the Bold and John the Fearless. The latter had him assassinated in the Marais quarter in Paris on November 23, 1407. His widow, Valentine Viscounti, daughter of the Duke of Milan, retired to Blois where she passed away the following year.
Taking advantage of the conflict between the houses of Orléans and Burgundy, the English invaded France and defeated the French knights at the battle of Agincourt. The elder son of Louis I, Charles of Orléans (1394-1465), who had inherited the château, was taken prisoner. His predilection for poetry helped him to resist 25 years of captivity in London. He returned to France a widower, and at the age of 50, married Marie of Clèves who was only 14 years old.
During his captivity, his half brother Jean, the « bastard » of Orléans, illegimate son of Louis of Orléans, managed his estate and and negociated his release. A companion in arms of Joan of Arc, Jean was granted the County of Dunois (since detached from the County of Blois) in 1440 in gratitude for his loyalty. After his liberation, Charles of Orléans abandonned all political ambitions and made Blois his favorite residence. He tore down part of the old fortress and built a more confortable residence. Charles surrounded himself with a small circle of artists and scholars and took the poet François Villon under his protection. In 1462, his wife Marie of Clèves gave birth to their son Louis in Blois.
At the death of his father Charles in 1465, the young Louis became the Duke of Orléans and Count of Blois under the name of Louis II. In order to avoid that he have a descendance and become a political rival, King Louis XI forced Louis to marry his daughter Jeanne of France, who was both disabled and sterile. Their engagement was negociated in 1464, and their marriage was celebrated in 1476. At war with his cousin Charles VIII and his sister, the Regent Anne of Beaulieu, the rebellious duke escaped from Blois and sought refuge at the court of the Duke of Brittany.
Imprisoned by the King at the end of the so-called Mad War, Louis of Orléans finally obtained the good graces of Charles VIII and fought at his side in Italy in 1494. The accidental death of the King, whose two sons had died a short time before, occurred at the Château of Amboise on April 7,1498. As a consequence, his cousin, the Duke of Orléans, mounted the throne under the name of Louis XII. In accordance with her marriage contract, Anne de Bretagne accepted to remarry the next king with whom she had two daughters.
Thus the Château of Blois became a royal residence.