The Battle of Arnemuiden, in which a French force defeats the English, is the first naval battle of the Hundred Years' War and the first naval battle in which gunpowder artillery is used.

The Battle of Arnemuiden was a naval battle fought on 23 September 1338 at the start of the Hundred Years' War between England and France. It was the first naval battle of the Hundred Years' War and the first recorded European naval battle using artillery, as the English ship Christopher had three cannons and one handgun.

The Hundred Years' War was a conflict between the kingdoms of England and France and a civil war in France during the Late Middle Ages. It emerged from feudal disputes over the Duchy of Aquitaine and was triggered by a claim to the French throne made by Edward III of England. The war grew into a broader military, economic, and political struggle involving factions from across Western Europe, fuelled by emerging nationalism on both sides. The periodisation of the war typically charts it as taking place over 116 years. However, it was an intermittent conflict which was frequently interrupted by external factors, such as the Black Death, and several years of truces.

September 23 is the 266th day of the year in the Gregorian calendar; 99 days remain until the end of the year.