* The rivalry between England and France. The two countries had been competing for control of territory in France for centuries. This rivalry was exacerbated by the fact that the English kings also held the title of Duke of Normandy, a French province.
* The disputed succession to the French throne. In 1328, the French king Charles IV died without a male heir. This led to a dispute over who should succeed him. The two main claimants were Edward III of England, who was Charles IV's nephew, and Philip of Valois, who was Charles IV's cousin.
* The English desire to control trade in France. England was a major trading nation, and it wanted to have access to the French market. This desire was hindered by the fact that the French kings often imposed high tariffs on English goods.
* The role of nationalism. By the 14th century, nationalism was beginning to emerge as a force in European politics. This led to a desire on the part of the English and French to assert their national identities and to defend their territories.
The Hundred Years' War was a long and bloody conflict that had a profound impact on both England and France. It led to the loss of English territory in France, the rise of nationalism, and the development of new military technologies.