The Battle of Winchelsea or the Battle of Les Espagnols sur Mer ("the Spaniards on the Sea") was a naval battle that took place on 29 August 1350 and was a victory for an English fleet of 50 ships, commanded by King Edward III, over a Castilian fleet of 47 larger vessels, commanded by Charles de La Cerda. Between 14 and 26 Castilian ships were captured, and several were sunk. Only two English vessels were sunk, but there was a significant loss of life. The battle was part of the Hundred Years' War between England and France.

England's trade, its war finance and its ability to bring force to bear against France were heavily reliant on seaborne transportation, especially to its territory in Gascony. With its own ability to raise and support a fleet much reduced by English activities, the French hired Castilian ships to blockade English ports. Frustrated by their effectiveness, Edward III himself led the fleet that intercepted them and inflicted heavy losses. In spite of that success, English trade and ports saw little relief from naval harassment by the French and their allies.