A combination of dynastic disputes, feudal quibbles, trade disagreements and historical antagonism resulted in the opening of the Hundred Years War in 1337. The first major English land victory in this conflict was the Battle of Crécy (1346). This pitted the French army, then considered the best in Europe, against the English under King Edward III. The battle established the longbow as one of the most feared weapons of the medieval period, a reputation reinforced at the bloody Battle of Poitiers (1356) where much of the French nobility was slaughtered and their king captured by the English host.
The Armies of Crécy and Poitiers by Christopher Rothero