The Battle of Sluys (; ), also called Battle of l'Ecluse, was a sea battle fought on 24 June 1340 as one of the opening conflicts of the Hundred Years' War between England and France. The encounter was during the reigns of Philip VI of France and Edward III of England, in front of the town of Newmarket or Sluis, (French Écluse), on the inlet between West Flanders and Zeeland.