Battle of Sluys (1340) — key naval engagement of the Hundred Years' War

The French fleet arrived at the mouth of the Scheldt on 8 June, first sacked the island of Cadzand and then went into waiting position, reinforced in the following days by eleven more Castilian and Flemish ships loyal to France. As a large number of the French galleys had been destroyed in an English attack earlier in the year, the assembled fleet consisted mainly of merchant ships, which were of very limited use in offensive operations. The two commanders of the French fleet, Nicolas Béhuchet and Hugues Quieret therefore chose to wait in place for Edward to arrive. Just before the battle, the French ships were to set up like a barrier in the Zwin and block the entry of the English. Owing to various delays, the English fleet could not be assembled in the mouth of the Orwell off Ipswich until June 20, 1340. On the 22nd this passed Harwich, and finally arrived off the Flemish coast on the 23rd of June.

As soon as the English came in sight, a council of war was held on the French fleet. Pietro Barbavera, the commander of the Genoese mercenary galleys, referred to the wind favouring the English and repeatedly called for an immediate attack by the numerically superior French fleet. Admirals Béhuchet and Quieret, however, stuck to their blockade strategy. The French ships were eventually arranged in three lines across the width of the Zwin, with the largest ships forming the front line. Among the foremost ships were the very large English ships "Cog Edward" and "Christopher" captured two years earlier in the naval battle of Arnemuiden. All ships of a line were connected with long iron chains to prevent the English from slipping through.

The English fleet first anchored at Blankenberge, and a council of war was also held there. It was agreed that a small reconnaissance party should be sent ashore first, in order to be able to inspect the French fleet from a greater distance. After the return and report of the party it was decided to wait with an attack until the next day, if the favourable winds would still be supported by the tide pushing into the Scheldt estuary.

The shores surrounding the Zwin were by now populated with thousands of onlookers, some armed, eager to watch the impending battle.

Early in the afternoon of 23 June 1340, the English fleet began its entry into the Zwin. The ships were formed in three lines, just as the French had been, with the largest ships in front. The formation of the French, linked by chains, had fallen into some disorder since the day before. A slight current had driven the ships eastward toward the island of Cadzand, in front of which they finally all lay side by side in three rows. When the French became aware of the impending attack of the English, the chains between the ships were hastily loosened, and an attempt was made to recapture the dispersed line formation of the previous day across the whole breadth of the Zwin. This scheme failed in the shortness of time, and soon the French fleet was thrown into some disorder. One ship of the first line, the "Riche de Leure," was thereby steered too far to the north, and occasionally got first into the approaching English fleet.

As was customary in medieval naval battles, the following battles were primarily fought in direct hand-to-hand combat between the crews. With the help of grappling hooks and throwing ropes, they tried to capture the enemy ship, moor it to their own ship, and then storm it. A few warships also had ballistae and slingshot machines mounted on board, but these usually caused little damage and had mainly a psychological effect. The archers and crossbowmen on board the ships were usually positioned in the masts or other superstructures - sometimes on platforms specially mounted for this purpose - in order to cover the enemy with projectiles from above.

The fighting was carried on with very great severity, and lasted from about 3 p.m. in the afternoon until sometimes far into the night. Even though the English fleet was outnumbered in men and ships, it soon prevailed in the hand-to-hand fighting. Partly this was because the English longbowmen shot faster and more accurately than the crossbowmen of the French fleet. Secondly, the English ships carried the invasion force intended for Flanders, which were vastly superior in training and equipment to the French ships, which were manned mainly by sailors from Normandy. The fact that the English fleet consisted largely of merchant ships and included few actual warships was immaterial to the battle itself, since the French were defending a fixed point and speed and maneuverability of the ships were therefore of little consequence.

At about 7 p.m. the first line of the French fleet had been fought down and the English fleet continued to push towards the second line. Now the English were at a distinct advantage, having lost none of the large ships standing in their first line, and now encountering mainly the smaller French units. Moreover, by now they had the sun at their backs, which put the French crossbowmen at an additional disadvantage. By nightfall, the remaining French lines broke apart and the battle dispersed into many small skirmishes across the Zwin. As the outcome of the battle began to become clear in the early evening, the Flemings watching on the riverbanks intervened in the action. In small groups they guarded the shore or manned small rowboats and slew all the French they could get hold of.

About 10 p.m. the fighting visibly slackened and the few remaining French ships turned to flee. Only the "Saint-Jame" from Dieppe and a ship from Sandwich were so entangled that they could not break away and the fighting continued until dawn. A total of 23 French ships succeeded in escaping the slaughter, among them the six galleys of Barbavera, which, in view of the impending defeat, had already retreated early in the evening, and four of the barques, which escaped in the gathering darkness. A further 13 ships made a surprise escape into the English Channel at dawn. A pursuit of the escaping ships set by John Crabbe directly the next morning was unsuccessful.

On the ships left behind no pardon was granted by the English, all wounded and captured were killed. The Flemings additionally made sure that even an escape into the water remained almost hopeless. Among the dead were the two admirals Quieret and Béhuchet. Quieret fell in battle while storming his ship, while Béhuchet was taken alive and then promptly hanged from the mast on Edward's orders - as revenge for the naval battle of Arnemuiden.