The Hundred Years War was a vicious, costly, and, most dramatically, drawn out struggle that laid the framework for the national identities of both England and France into the modern era. The first twenty years of the war were positive for the English, by any account. They already held the South of France, through Eleanor of Aquitaine's dowry, and were allied with the Flemish in the north. After the brilliant naval battle of Sluys, the English had...