Causes of the Hundred Years' War: From the Norman Conquest to 1337

The Hundred Years’ War had no single cause. The conflict of 1337–1453 grew out of a century and a half of structural tension between the English and French monarchies, sharpened by the dynastic accident of 1328. Disentangling the immediate trigger from the underlying pressures is the work of a century of modern scholarship: Édouard Perroy’s La Guerre de Cent Ans (1945) put the structural causes on the historiographical map; Jean Favier’s La Guerre de Cent Ans (1980) and Philippe Contamine’s La Guerre de Cent Ans (1968) are the standard French syntheses; Jonathan Sumption’s The Hundred Years’ War (vol. I 1990) is the English-language reference.

The succession crisis of 1328

The immediate trigger was the death of Charles IV of France on 1 February 1328, the last direct male Capetian. The two leading claimants were Edward III of England (whose mother Isabella was Charles IV’s sister) and PhilipCount of Valois (a cousin of the late king through the male line). The French magnates applied the Salic Law — by interpretation rather than explicit provision, since the law had never been used to settle a regnal succession in this way — and chose Philip, who was crowned at Reims on 29 May 1328 as Philip VI.

The English position was not hopeless. Edward did homage to Philip for the duchy of Aquitaine at Amiens on 6 June 1329, but the homage was compromised by being made on behalf of a regency (Isabella and Mortimer) that was dependent on French goodwill. When Edward overthrew the regency in October 1330 and assumed personal rule, the constitutional case for reopening the question was intact. The case for the war was not made by a single dramatic act, but by a slow accumulation of small disputes through the 1330s.

The feudal relationship

The structural cause lay in the constitutional absurdity of the Anglo-French feudal relationship. The English king had been vassal of the French king for continental possessions since 1066, when William of Normandy became king of England. Under Henry II, the Plantagenet dominions in France — Normandy, Anjou, Aquitaine, Maine, TourainePoitou — formed a single cross-Channel realm larger than the French royal domain. The loss of Normandy, Anjou, Maine, and Touraine under John (1202–1204) and the loss of the rest of the Angevin inheritance under Henry III left the English kings with a single continental duchy, Aquitaine, which the Valois kings treated as a fief and the Plantagenet kings treated as a patrimony.

The dispute over the manner of the homage — should it be liege homage (the liege lord) or simple homage; should it be done in person or by proxy; should it be done before or after other ceremonies — was the running sore of the 1330s. Philip VI used the case of Robert d’Artois (banished from France in 1332, given refuge by Edward) to bring the matter to a head. The Parlement of Paris, sitting in Edward’s absence, declared Aquitaine forfeit on 24 May 1337.

Aquitaine

Aquitaine was the most valuable of the surviving English possessions — the wine of Bordeaux paid for much of the English war effort, and the duchy was governed directly by the Black Prince from 1362 to 1372. The duchy was also the most legally entangled: a duchy held as a fief of the French crown, whose dukes were also kings of England, and whose subjects were French-speaking but politically English. The Aquitanian question is treated separately in the duchy of Aquitaine article; the English case is set out in the English territorial claims article.

The economic dimension

By the early 14th century the English economy was structurally dependent on the export of raw wool, and most of that wool went to the cloth towns of Flanders — Ghent, BrugesYpres — which sat under French feudal suzerainty. The French crown had an interest in diverting that trade; the English crown had an interest in defending it. The political levers on both sides were strong. Edward I had set up the company of the staple in the 1270s, which required English wool to be exported through designated continental ports (initially in England, later in Calais); the French had periodically retaliated by seizing English merchants’ goods and by closing Flemish ports to English wool.

The economic causes of the war are too often subordinated to the dynastic and feudal ones. Anne Curry’s work in particular has shown that the wool trade was the necessary financial pre-condition of every Edwardian campaign. For a fuller treatment, see economic causes.

The Scottish and Flemish alliances

Two long-running alliances shaped the diplomacy of the war.

The Auld Alliance of 1295 bound France and Scotland. It was renewed by Philip VI in 1326 and again in the 1330s. The English invasions of Scotland under Edward III in 1335 and the French subsidies of the Scottish resistance kept the northern war alive for the entire Edwardian phase. The Franco-Scottish dimension is treated in what was the Auld Alliance.

In Flanders, the count of Flanders was a vassal of the French crown, but the cloth towns had their own interests and depended on English wool. The English cultivated the Flemish cities through subsidies and trade concessions throughout the war; the French response — direct control of Flanders, achieved in 1384–1385 under Philip the Bold of Burgundy — was one of the more durable strategic gains of the Caroline phase.

The role of personality

Structural causes explain the possibility of war; the specific decisions of the 1330s explain its outbreak. Philip VI was a cautious and indecisive king, more a feudal magnate than a national monarch, dependent on a narrow group of advisors. Edward III was young, ambitious, militarily capable, and had spent his minority watching his mother and her lover Mortimer run the country. The personality question is not whether one man was better than the other — both made mistakes — but whether either of them was temperamentally equipped to manage the slow, technical diplomacy that the situation required. Neither was.

The long view

The Hundred Years’ War is, in the long view, the working-out of two parallel processes: the contraction of the English Plantagenet empire and the consolidation of the French Valois monarchy. The duchy of Aquitaine was the last surviving fragment of a world in which the King of England was also a great continental lord. The French monarchy, from Philip Augustus to Philip VI, was the agent of that contraction. The war was the moment when the process became explicit and violent.

The causes of the war are best read together with the English territorial claims, the Duchy of Aquitaine, the economic causes, the Salic Law, and the Auld Alliance.