The English had no purpose-built warships, so had to make do with deep-draught, round-hulled merchant ships, known as cogs, that were converted for naval duties. Edward assembled a combined fleet at Orwell, in Kent and set up his headquarters on the "cog Thomas" . Although he knew that the French fleet was a far superior force to his own he sailed with his fleet on 22 June to confront the French fleet a day later. The French fleet assumed a defensive formation off the port of Sluys, possibly trying to prevent Edward from landing his army. The English fleet apparently tricked the French into believing they were withdrawing. However, when the wind turned in the late afternoon, the English attacked with the wind and sun behind them. Edward sent his ships against the French fleet in units of three, two ships crammed with archers and one full of men-at-arms. Because the ships of the French fleet were so close together it limited their maneuverability. The English ships with the archers would come alongside a French ship and rain arrows down on its decks, the men-at-arms would then just mop up. The French fleet was almost completely destroyed in what became known as the Battle of Sluys. England dominated the English Channel for the rest of the war, preventing French invasions.