Final answer:
The Hundred Years' War was caused by a dispute between England and France over claims to French lands held by the English monarch. This conflict led to political factionalism and devastation, particularly in France.
Step-by-step explanation:
The Hundred Years' War (1337-1453) was caused by a dispute between England and France over claims to French lands held by the English monarch. When King Charles IV of France died without a son in 1328, the crown was given to his nephew Philip, the Count of Valois. However, King Edward III of England maintained that he had the greater right to the throne of France due to his relation to Charles IV. This conflict led to political factionalism and devastation, particularly in France where most of the fighting occurred.