The Hundred years war was a conflict between the Plantagenet rulers of England and various French factions over the inheritance of the throne of France. It began with initial English successes which were reversed some years later. However, the ebb and low of successes and failures were complicated by internal factors which weakened England, thereby resulting in English failure.
Edward the Third
In 1328, the king of France died childless, leaving factions among the nobility contending for power. Edward the Third of England had a good claim to the throne, but a French faction crowned a more distant cousin. War began. Initially, the English was successful. In 1340, French and Spanish naval forces planning a seaborne invasion of England were heavily defeated at Sluys, off the Netherlands.
The English forces, battle-hardened against Scots and Welsh and well-equipped with long bowmen, had initial success. In 1346, these English forces had a significant victory at Crecy and they eventually took Calais.
English control of the Channel was an important military advantage at that time. Matters at this time were complicated by the Black Death which ravaged Europe and slowed down conflicts.
However, in 1356, the English were still capable of inflicting a major defeat on the French at Poitiers, where the French king was captured. He later died in captivity. By 1360, a peace treaty left England in control of much of Western France.
In 1381, the peasants' revolt distracted English attention and gave the French encouragement to recover land. The 1380s saw French recovery in which French forces, having recovered access to the Channel at Rouen, attacked and ravaged the Isle of Wight.
England then suffered internal problems through the Wars of the Roses. In a delicate state, it could not resist French attempts at recovery of territory and English power was severely weakened, being reduced to a few towns, one of which was Calais.
However in 1407, internal divisions in France encouraged the English kings. Henry the Fifth invaded and in 1415, he routed the French at the battle of Agincourt. English power was established and in a treaty, Henry was acknowledged to be the heir to the French throne.
However, French resistance flared up and under Joan of Arc, who inspired French forces, the English were steadily driven back as cities under English control fell. England's internal weaknesses through the renewed wars of the Roses had much to do with this failure.
Successive English defeats followed and in 1453, the war ended with French victory. England was left wit only Calais and the Plantagenet lands in France were all lost.