From Wikipedia The Hundred Years' War was a conflict between France and England, lasting 116 years from 1337 to 1453. It was fought primarily over claims by the English kings to the French throne and was punctuated by several brief and two lengthy periods of peace before it finally ended in the expulsion of the English from France, with the exception of the Calais Pale. Thus, the war was in fact a series of conflicts and is commonly divided into three or four phases: the Edwardian War (1337-1360), the Caroline War (1369-1389), the Lancastrian War (1415-1429), and the slow decline of English fortunes after the appearance of Joan of Arc, (1412-1431). The term "Hundred Years' War" was a later historical term invented by historians to describe the series of events.
The war owes its historical significance to a number of factors. Though primarily a dynastic conflict, the war gave impetus to ideas of both French and English nationality. Militarily, it saw the introduction of new weapons and tactics, which eroded the older system of feudal armies dominated by heavy cavalry. The first standing armies in Western Europe since the time of the Western Roman Empire were introduced for the war, thus changing the role of the peasantry. For all this, as well as for its long duration, it is often viewed as one of the most significant conflicts in the history of medieval warfare.