What caused the Hundred Years' War – in a nutshell

Generally dated 1337–1453, the Hundred Years’ War was a succession of conflicts between the English House of Plantagenet and the French House of Valois over the succession to the French throne. As inheritors of the holdings initially owned by William, Duke of Normandy (later, the Conqueror), and augmented by Henry II’s Angevin Empire that by 1337 consisted only of Gascony, the Plantagenet Kings of England had long ruled over large areas of France as vassals of the French King.

When Charles IV died with no male heir surviving into adulthood, and thanks also to a principle established in French law that no female could succeed to the throne, Charles’s sister, Isabella, widow of Edward II of England, attempted to seize the throne for her son Edward III by right of blood succession as the nephew of Charles IV and grandson of Phillip IV. Although her motion was rejected by the French, leading to count Phillip of Valois – grandson of Phillip III and nephew of Phillip IV – being accepted by the English as King of France, Phillip’s meddling in Edward III’s war with Scotland saw Edward reassert his claim.

Despite the great victories at Crécy, Poitiers and Agincourt that paved the way for Henry VI of England to become the disputed ruler of France 1422–53, the large number of French resources eventually led to Valois dominance and the end of the war.