Why is it called the Hundred Years War?

The Hundred Years' War refers to the war between England and France for a little more than a century, form 1338 till 1453. Of course, the war did not, indeed, go on all the time in the period mentioned. There were recesses and truces now and then, and often some of them were long enough. Nevertheless, for a little more than a hundred years England and France remained enemies. The war actually covered the reign of five English kings and caused death to the numerous soldiers of both sides.

The war may be divided into the two periods of great success and of the two periods of drastic failure for English power. The first period covered the early part of the reign of Edward III. The English won in the Battles of Crecy and poietiers and the French king was forced to admit the English claim on the south west of France that was followed by a time of decline in the later part of Edward III's reign and of total failure in Richard II's time. The French force landed on Sussex and occupied the English territories.

The second wave of the English success started with Henry IV and reached its crest with Henry V. The latter's victory in the Battle of Agincourt was a memorable achievement. The king married the daughter of the French king and became his heir. Even his Infant son Henry VI was crowned in Paris as a king of France. 

But then came the second phase of dismal failure for the English. The English power was shaken by the miracle of Joan of Arc and the English forces were driven out of France. By degrees all was lost that had been wrongly won. And in 1453, at the time of the end of the long war, nothing was left to England in France, save Calais.