In reality, peace is not lasting. The delays brought about in the transfer of the territories for the benefit of England gave Edward III the opportunity to resume his dynastic claims, while John the Good, for his part, by not ratifying his renunciations, implicitly retained his rights over the lost provinces. In addition, Jean le Bon's ransom was not paid on time. It is true that Edward III holds as collateral six princes of the fleur-de-lys:brother, son or relative of the king. But one of them, the Duke of Anjou, having slipped away from his guards, in September 1363, Jean le Bon believed himself morally obliged to constitute himself a new prisoner. He died during this second captivity, April 8, 1364 - On the continent, a new source of conflict arose in November 1361, when Philippe de Rouvres, Duke of Burgundy died without leaving a direct heir. Two candidates can claim the duchy Charles le Mauvais and Jean le Bon, respectively grandson and son of the late duke's great-aunt. Jean le Bon, who finds himself judge and party, decides in his favor and makes his new acquisition a prerogative for his son Philippe, thus laying without knowing it the bases of the Burgundian State which will threaten to overwhelm his successors. In the immediate future, the Navarrese refuses any arbitration, but he is beaten at Cocherel, near Vernon, by Bertrand du Guesclin in 1364. A treaty, concluded in March 1365, grants him the co-lordship of Montpellier but removes all his places of the lower Seine downstream of Paris.
The struggle also continued in Brittany between the supporters of Jean de Montfort, son of the first Jean de Montfort, still supported by England, and those of Charles de Blois, freed in 1356 after a long captivity. In 1364, Charles de Blois was defeated and killed at Auray by Jean de Montfort. Du Guesclin, who assisted him, was taken prisoner. Charles V was then forced to negotiate:by the Peace of Guérande (April 1365), he recognized Jean de Montfort as Duke of Brittany, but in exchange, the latter had to pay homage to him, thus bringing his stronghold back into the movement of the King of France.
The King of Navarre neutralized, the quarrel of Brittany settled, remains the problem of the Companies, armed groups which, most often, had been in the pay of a legitimate authority but, once broken, refused to disperse and continued the war. for their own account. In 1360 and 1368, on several occasions, the Companies met to give birth to real armies, called Great Companies. Spain provided them with an outlet in 1365-1366 under the leadership of du Guesclin, well suited to understand and command them, they put themselves at the service of Henri de Trastamare who, with the support of Charles V, claimed to hunt du throne of Castile the unpopular Peter the Cruel. The latter was finally defeated and killed by the hand of his rival at Montiel in May 1369. In the affair, Charles V won the lasting support of Castile and rid France of the Compagnies which, in the last years of the century , will be no more than a local plague.
The succession of Flanders could have constituted a serious danger for Charles V. While his father, Louis de Nevers, had always held for the Valois, Louis II de Male, his successor, thought after 1360 of getting closer to Edward III. He even thinks of giving his only heiress, Marguerite of Flanders, widow of Philippe de Rouvres, Duke of Burgundy, in marriage to one of the sons of Edward III. But the diplomacy of Charles V succeeded in dismissing this project. On the contrary, in 1369, it was Philippe le Hardi, duke of Burgundy, who married Marguerite of Flanders. If the union of Flanders and Burgundy should later prove dangerous for France, no one could have foreseen it and, at the time it was done, it offered decisive support for the King of France.
The horizon of the French monarchy has therefore been singularly cleared up and, on both sides, no one seems to be seriously considering the resumption of hostilities. Circumstances will decide otherwise. Edward III grouped all his possessions in the south-west into a vast principality of Aquitaine, which he entrusted to his eldest son, the Black Prince. The latter set up an efficient, rigorous administration, but his interventions in Castile disrupted his finances and forced him to levy new taxes. Protests are on the rise. The most violent comes from the Count of Armagnac who asks for the arbitration of Charles V. Indeed, until the exchange of renunciations which has still not taken place, the King of France retains sovereignty in the ceded territories. Accepting the appeal of the Count of Armagnac, Charles V summons the Black Prince to appear before the Parliament of Paris. Froissart reported the answer of the English prince, full of superb:"We will gladly go to Paris on the day we are cited, since it is thus commanded by the King of France, but it will be the bassinet in the lead with 60,000 men of our company."
In response, Edward III regained the title of King of France on June 3. Finally, on November 30, Charles V once again pronounced the confiscation of Guyenne. On this date, hostilities had resumed for several months. Thus, unlike his two predecessors, with a combative and chivalrous reputation, but who had never taken the initiative in the war, Charles V, the "wise king" concerned with good government, whose health forbade him to campaign in person, lucidly carried out, in 1368-1369, a policy that could only lead to war, at a time when neither the Castilian problem nor the Flemish problem was solved.
The first French campaigns are crowned with success. At the end of 1377 the provinces lost seventeen years earlier were almost entirely recovered, and Charles the Bad, whose intrigues with the King of England and the Duke of Brittany had been revealed, saw his fortresses invested one by one by the Duke of Burgundy. However, the English still hold Calais, Bordeaux and Bayonne firmly. They still control a large number of fortresses in the center-west of France and succeeded in seizing Cherbourg. Finally Charles V suffered a failure in Brittany. When Duke John IV took refuge in England, he thought he could easily annex the duchy. This was to misunderstand the strength of Breton particularism. On his return, in 1379, Jean IV received an enthusiastic welcome, and Charles V had to restore his duchy to him (second Treaty of Guérande, April 1381).
The death, three years apart, of Edward III and then Charles V, and the accession of two very young kings, Richard II in England and Charles VI in France, created new conditions in the course of the conflict. In France, the uncles of the new king agree to jointly exercise power during his minority. The advisers of the previous reign, who had received the nickname of "marmosets" because of their often modest origin, are discarded. The completion of the work of reorganization undertaken by Charles V is neglected. Each of the uncles pursues his personal policy. Hence the continual intrigues and conflicts. Jean de Berry wants to make a fortune thanks to his lieutenancy of Languedoc, Philippe de Bourgogne thinks of Flanders, Louis d'Anjou in the kingdom of Naples. The new taxes levied to help the latter in his undertakings lead to popular unrest, notably in Rouen (the "Hérelle") and in Paris (revolt of the Maillotins). Anarchy also reached Ghent which, under the impetus of Philippe van Artevelde, son of the great politician of the 1340s, demanded an economic and military alliance with England. For the government of the uncles, the Flemish revolt is very dangerous. They bring together a strong army which crushes the Ghent militias at Roosebeke (1382). But, solicited by their personal interests, they are somewhat uninterested in the fight against England. For his part, Richard II had to face a serious peasant revolt in 1381. Under these conditions, the war stalled and a truce was finally concluded in 1388. Extended several times, it marked the beginning of a lasting rapprochement between France and England. A new phase of the conflict is beginning.