The first phase of the Hundred Years' War between France and England lasted from 1337 to 1360. It is sometimes referred to as the Edwardian War because it was initiated by King Edward III of England, who claimed the French throne in defiance of King Philip VI of France. The dynastic conflict was caused by disputes over the French feudal sovereignty over Aquitaine and the English claims over the French royal title. The Kingdom of England and its allies dominated this phase of the war.

Edward had inherited the duchy of Aquitaine, and as Duke of Aquitaine he was a vassal to Philip VI of France. Edward initially accepted the succession of Philip, but the relationship between the two kings soured when Philip allied with Edward's enemy, King David II of Scotland. Edward in turn provided refuge to Robert III of Artois, a French fugitive. When Edward refused to obey Philip's demands for the expulsion of Robert from England, Philip confiscated the duchy of Aquitaine. This precipitated war, and soon, in 1340, Edward declared himself king of France. Edward III and his son Edward the Black Prince, led their armies on a largely successful campaign across France with notable victories at Auberoche (1345), Crécy (1346), Calais (1347), and La Roche-Derrien (1347). Hostilities were paused until the mid-1350s for the deprivations of the Black Death. Then war continued, and the English were victorious at the Battle of Poitiers (1356) where the French king, John II, was captured and held for ransom. The Truce of Bordeaux was signed in 1357 and was followed by two treaties in London in 1358 and 1359.

After the treaties of London failed, Edward launched the Rheims campaign, which, though largely unsuccessful, led to the Treaty of Brétigny, which settled certain lands in France on Edward for renouncing his claim to the French throne. This was in part caused by Black Monday (1360), the freak storm that devastated the English army and forced Edward III into peace talks. This peace lasted nine years; but then began a second phase of hostilities known as the Caroline War.