Hundred Years' War
Historians commonly divide the war into three phases separated by truces: the Edwardian War (1337–1360), the Caroline War (1369–1389), and the Lancastrian War (1415–1453). Local conflicts in neighbouring areas, which were contemporarily related to the war, including the War of the Breton Succession (1341–1365), the Castilian Civil War (1366–1369), the War of the Two Peters (1356–1369) in Aragon, and the 1383–85 crisis in Portugal, were availed by the parties to advance their agendas. Later historians adopted the term "Hundred Years' War" as a historiographical periodisation to encompass all of these events, thus constructing the longest military conflict in European history.
Battle of Blanchetaque
Since the Norman Conquest of 1066, English monarchs had held titles and lands within France, the possession of which made them vassals of the kings of France. The status of the English king's French fiefs was a major source of conflict between the two monarchies throughout the Middle Ages. Over the centuries, English holdings in France had varied in size, but by 1337 only Gascony in south western France and Ponthieu in northern France were left. Following a series of disagreements between Philip VI of France () and Edward III of England, on 24 May 1337 Philip's Great Council in Paris agreed that the Duchy of Aquitaine, effectively Gascony, should be taken back into Philip's hands on the grounds that Edward was in breach of his obligations as a vassal. This marked the start of the Hundred Years' War, which was to last one hundred and sixteen years. In 1340, Edward formally assumed the title King of France.