The Hundred Years’ War was actually a series of conflicts between the Plantagenet kings of England and the Valois kings of France. On the surface, the war was over the succession to the throne of France.
In 1314, Philip IV of France died. He was the last of the Capetian kings and left three potential heirs: Louis X, Philip V, and Charles IV. He also had an illegitimate daughter, Isabella, who had been married to the English king Edward II of England and had given birth to a son in 1312, Edward of Windsor.
When Louis X died in 1316 without issue, and then his brother Philip V died in 1322, Charles IV inherited the throne of England. When he died in 1328 without a male heir, the issue of succession became hotly contested. Edward of Windsor, now King Edward III of England, believed that as the closest male relation to Philip IV (his grandfather), he was the rightful heir to the French throne.
The French nobles argued that the Salic Law required the passage of the throne through a male child, thus since Edward was related to Philip IV through his mother, he was ineligible. They crowned another descendant of Philip III, Philip of Valois, as king of France.
Philip of Valois was the son of Philip IV’s brother Charles of Valois, so he was Edward’s great uncle. The English protested but did not take any martial actions.
Then, in 1333, Edward III made war on Scotland, and Philip of Valois, now Philip VI of France, moved to take the last English footholds in France, coastal Gascony. Edward continued to deal with Scotland through a general and rushed to defend his holdings in France.
This first part of the war is called “The War of Breton Succession” and lasted from 1337 until 1360. It was marked with the end of ‘chivalrous war’ with the Battle of Crécy in 1347 when English longbowmen decimated the French nobility. Later, in 1356, Edward’s son, known as “The Black Prince” invaded France and even captured the French king, John II at the Battle of Poitiers in 1358.
John was held for ransom, but the French could not raise the money so he remained in English hands until the French traded Acquitaine for him. Then, the Dauphin, John’s soon-to-be-successor Charles V, successfully held off the English advances until finally the two sides signed the Treaty of Brétigny in 1360.
The peace lasted until 1369, when the now King of France, Charles V, recognized the potential for victory and renewed the conflict. With the Black Prince busy in Iberia, and Edward III aging and close to death, Charles attacked anew. The French won resounding victories and the English finally sued for peace in 1389.
This peace lasted until 1415 when the reign of the mad king Charles VI resulted in a French civil war between his brother John the Fearless and his cousin Louis of Orléans. The English then invaded France to solve the rivalry, and were largely successful in their campaigns until the French gained help from an unlikely source.
Joan of Arc, a peasant girl, claimed to have received messages from God. For some reason, the Dauphin (Charles VII) listened to her and broke a siege in Orléans. After that, the French fought steadily forward until expelling the English from France in 1453 and declaring all Plantagenet claims to French land or the French crown void.
Not ironically, 1453 was the same year that Constantinople fell to the Turks – largely because all of Western Europe was consumed and tied into the Hundred Years’ War. But that’s a matter for another time.