The document provides background information on the Hundred Years' War between England and France from 1337 to 1453. It discusses the origins of the war over conflicting claims to the French throne by the English and French kings. The war occurred in four phases and saw shifts from ideals of chivalry to more modern warfare with hired mercenaries and use of gunpowder weapons. The war weakened both countries and drew in other powers like Burgundy and the Ottoman Empire, whose conquest of Constantinople in 1453 marked the end of the Byzantine Empire.