In 1328 the Capetian monarchy had its first succession crisis, which led directly to the ruinous Hundred Years War with the English. Charles IV, last of the line, had only daughters as heirs, and when it was decided that France could not be ruled by a queen, the English king, Edward III , whose mother was Charles's sister, claimed the throne of France for himself.

The French chose Philippe, Count of Valois , instead, and Edward acquiesced for a time. But when Philippe began whittling away at his possessions in Aquitaine, Edward renewed his claim and embarked on war. Though, with its population of about twelve million, France was a far richer and more powerful country, its army was no match for the superior organization and tactics of the English. Edward won an outright victory at Crécy in 1346 and seized the port of Calais as a permanent bridgehead. Ten years later, his son, the Black Prince, actually took the French king, Jean le Bon, prisoner at the battle of Poitiers .

Although by 1375 French military fortunes had improved to the point where the English had been forced back to Calais and the Gascon coast, the strains of war and administrative abuses, as well as the madness of Charles VI, caused other kinds of damage. In 1358 there were insurrections among the Picardy peasantry (the jacquerie ) and among the townspeople of Paris under the leadership of Étienne Marcel. Both were brutally repressed, as were subsequent risings in Paris in 1382 and 1412.

The king's madness led to the formation of two rival factions, following the murder of his brother, the duke of Orléans, by the duke of Burgundy. The Armagnacs gathered round the young Orléans, and the other faction round the Burgundians . Both factions called in the English to help them, and in 1415 Henry V of England inflicted another crushing defeat on the French army at Agincourt . The Burgundians seized Paris, took the royal family prisoner and recognized Henry as heir to the French throne. When Charles VI died in 1422, Henry's brother, the duke of Bedford, took over the government of France north of the Loire, while the young king Charles VII ineffectually governed the south from his refugee capital at Bourges.

At this point Jeanne d'Arc arrived on the scene. In 1429 she raised the English siege of the crucial town of Orléans and had Charles crowned at Reims. Joan fell into the hands of the Burgundians, who sold her to the English, resulting in her being tried and burnt as a heretic. But her dynamism and martyrdom raised French morale and tipped the scales against the English: except for a toehold at Calais, they were finally driven from France altogether in 1453.

By the end of the century, Dauphiné, Burgundy, Franche-Comté and Provence were under royal control, and an effective standing army had been created. The taxation system had been overhauled, and France had emerged from the Middle Ages a rich, powerful state, firmly under the centralized authority of an absolute monarch.