Battle of Sluys

Setting the scene

The Battle of Sluys, fought on June 24, 1340, was the first major naval battle of the Hundred Years' War and one of history's largest naval engagements. Edward III of England claimed the French throne through his mother Isabella and had begun the war in 1337. By 1340, he needed to transport an army to Flanders to support his allies. The French, under admirals Hugues Quiéret and Nicolas Béhuchet, assembled a fleet of 200-250 ships, mostly converted merchant vessels, in the Zwyn estuary near Sluys (modern Sluis, Netherlands) to block him.

What happened

Edward gathered 120-150 ships and sailed from Orwell on June 22. On June 24, he attacked the French fleet, which was anchored in three lines and lashed together—a defensive formation that proved fatal. The English, with superior longbowmen, attacked at dawn with the sun and wind behind them. They first defeated the Genoese mercenary galleys on the flanks, then closed with the main French line. The battle became a melee, with English archers sweeping French decks and men-at-arms boarding. The French, trapped by their lashed ships, could not maneuver.

Why it still matters

Sluys was a total English victory. French losses were catastrophic—16,000-20,000 dead, including both admirals (Béhuchet was hanged from his mast), and nearly their entire fleet captured or sunk. English losses were minimal. The battle gave England control of the English Channel for decades, enabling Edward's campaigns in France, including Crécy (1346). It destroyed French naval power and forced France to rely on Castilian allies for fleets. Sluys demonstrated the effectiveness of the longbow at sea and established English naval dominance that would last, with interruptions, for centuries.

Background

It secured English maritime supply during the Hundred Years War. Even centuries later, this episode remains a reference point for how empires rise, fracture, and transform.