The Battle of Sluys (a Flemish word pronounced ‘Slois’) is not as well known as other English victories in the Hundred Years War like Crécy, Poitiers, or Agincourt. This is odd, as it was England’s first great naval victory, and the bloodiest medieval naval battle.
The French fleet was routed, just three years into a war that would henceforward be fought on French, rather than English soil. And, like most English victories at this time, the longbow was crucial.
The French offensive
King Edward III of England claimed the French crown through his mother Isabella, despite French law forbidding inheritance through the female line.
In 1338, the French had raided Jersey and burnt Portsmouth, Southampton, and Hastings. They then captured all the ships in Plymouth harbour.
The following year they seized the Christopher and the Edward while the ships were in German ports trading wool. This was an act of economic warfare given how important wool was to the English economy (even to this day, the Lord Chancellor’s seat is called the Woolsack).
Flanders, highly dependent on the cross-Channel wool trade, then switched to the English side. King Philip VI of France responded with a plan first to subdue the Flemings and then to invade England.
He tried and failed to bribe Flemish nobles with castles and debt relief. So, with the Pope’s blessing, he assembled his fleet at Honfleur in Normandy, and then dispatched it to Flanders on 26 May 1340.
When the French reached the Scheldt estuary, they blockaded Bruges by closing the Zwin river and tidal inlet, creating panic among a town population heavily dependent on maritime trade.
The French then pillaged the island of Cadzand, capturing merchant ships and killing the crews. Antwerp feared it would be next.
Ghent’s fortifications were reinforced on 11 June, and two days later Sluys received 400 sergeants (billmen) and 100 archers. Philip’s army, meantime, was moving on Hainault (on the present-day French–Belgian border).
The French king assembled his fleet at the estuary between Sluys and Blankenberghe. Sluys was the main Flemish port and was then considered the best harbour in Europe.
The English response
Unlike Philip, Edward had no standing navy, only three warships. He planned to take 40 ships to aid his allies in Flanders and to avenge the earlier sacking of English ports. However, as disturbing news came in of the size of the French fleet, he paused to build up his strength.
He banned ships in London from travelling abroad and asked the other ports for reinforcements, which arrived rapidly. Edward, appealing to their materialistic side, promised his sailors that they could keep ‘whatever they were able to lay their hands on’.
One English ship was full of noblewomen guarded by archers on their way to Queen Philippa in Ghent; all but one would survive the battle.
At 6am on 22 June, the English fleet left Orwell harbour. King Edward himself sailed on the Thomas.
At 9am the next day, the English sighted the Flemish coast. They were informed of the enemy’s location at the mouth of the Zwin by two merchants, Conrad Clypping and Peter de Gildesburgh.
At noon, they approached the village of Heist, where they attempted to rouse the Flemish against the French invaders.
The English had advanced so rapidly that the French had not been able to recruit locally. The English had planned to attack them in the Zwin at high tide, when it would be hardest for survivors to swim to safety. Realising they were too late, they delayed the attack until the next day.
Most of the ships on both sides were converted merchant vessels. The two main types of ship at the time were rowed galleys and sailing vessels called ‘cogs’. Galleys were fighting ships, but they were more suited to the calmer waters of the Mediterranean than the stormy waters of the North Sea.
Cogs, on the other hand, had much smaller crews, since they depended on wind power. Edward preferred cogs, because they were harder to board than galleys and dangerous to ram – galleys could easily capsize if they rammed a cog. Cogs, moreover, were perfect for archers, because these could be deployed in wooden ‘castles’ fore and aft. Cogs had a typical displacement of 250 tonnes.
The earliest reference to European cannon is in 1326. We know of only three cannon at Sluys, all on the captured English ship Christopher, but there is no evidence that the French made any use of them. Sluys was, to all intents and purposes, a pre-gunpowder naval battle.
The main English weapon was the longbow. Originally developed in South Wales and then adopted after the English conquest, one of the earliest references to the longbow was at the Siege of Abergavenny in 1182. Giraldus Cambrensis wrote that the Welsh arrows were one metre long and had pierced a 10cm oak door; they were left there as a memento.
A trained longbowman could shoot an arrow every ten seconds to a maximum range of about 350m (though effective range was below 250m). They carried daggers for use in close combat, and wore gambesons for protection – padded shirts usually worn under chainmail, but not at sea, where chainmail was a liability.
Possibly two-thirds of the English were armed with longbows. The remainder were armed with throwing axes, battle-axes, two-edged swords, and stones. Axes proved much easier to use in close-quarters naval action than swords.
The French preferred the crossbow, which did not need much training or strength to use, and was also much easier to aim at a target. The problem was that even the best crossbowmen could not manage more than two bolts a minute, compared to half a dozen arrows a minute from an experienced longbowman.
Approach to battle
The Battle of Sluys is better understood as a land battle at sea than as a conventional naval battle. It began at 3pm on Saturday 24 June 1340. Sluys was an inlet between Zeeland and Flanders.
Both fleets were arranged in three divisions. The English fleet of about 130 ships was commanded by King Edward III and the Lord Admiral William de Clinton, 1st Earl of Huntingdon. They had 4,000 longbowmen, 1,500 men-at-arms (professional soldiers as opposed to levies), and an unknown number of sailors and soldiers.
By contrast, the French had no longbowmen, only 150 men-at-arms, 600 crossbowmen, and 18,000 soldiers and sailors, mainly from Normandy and Picardy. The crossbowmen – 400 out of 600 – were concentrated on the Christopher, whose position indicated where the French guessed that the main weight of the English attack would fall.
The French fleet of 213 ships was commanded by the Admiral of France, Hugues Quiéret, and the Grand Constable of France, Nicolas Béhuchet. It comprised six galleys, seven royal warships, 22 oared barges, and 178 converted merchant vessels.
The galleys were grouped in a squadron commanded by the Genoese mercenary Admiral Pietro Barbavera. Barbavera had urged his fellow commanders to attack the English at sea, where superior French numbers could be brought to bear and they could gain the weather gage.
According to the Chronographia Regum Francorum:
Barbavera, who was in his galleys, perceiving the advent of the English, said to the Admiral [Quiéret] and to Nicholas Béhuchet: ‘My lords, you now see the King of England with his fleet approaching us. If you believe me, the whole fleet ought to be moved on to the open sea; for if you remain here, the English, who have the wind, sun, and the flow of the water with them, will confine you so much that you will be able to help your ships only minimally.’ However, Nicholas Béhuchet, who knew better how to make a calculation than to fight naval battles, responded to him: ‘He is a coward who retreats from here and does not stand ready for the order of battle.’
It was claimed that Béhuchet, an accountant/treasurer, had saved money by recruiting fishermen instead of experienced soldiers. Whatever, the French commanders overruled Barbavera, preferring to stay in shallow water and fight on the defensive.
Worse, on 23 June they lashed each of their three divisions together with chains so that their left division was helplessly exposed when the English attacked. The French leaders had thought this would mean the English would have to break through three lines to enter the estuary. Instead, it would have meant the central and right divisions being unable to come to the left’s aid.
The chained ships drifted ashore overnight, making manoeuvres even more difficult. By the time the chains linking the ships had been cut, it was far too late for the fleet to redeploy.
Nonetheless, the French admirals may have judged correctly that their ships would have been incapable of fighting in the open sea. The smaller English ships were more nimble than the French.
The English attack
Our main source for the battle is Jean Froissart’s Chronicles. He described the formation of the English fleet as follows:
When the King’s fleet was almost got to Sluys, they saw so many masts before it, that they looked like a wood. The King asked the commander of his ship what they could be, who answered that he imagined they must be that armament of Normans, which the King of France kept at sea, and which had so frequently done him much damage, had burnt his good town of Southampton, and taken his large ship the Christopher. The King replied: ‘I have for a long time wished to meet with them. Now, please God and St George, we will fight them. Of a truth, they have done me so much mischief that I will be revenged on them if possible.’
The King then drew up all his vessels, placing the strongest in the front, and on the wings his archers. Between every two vessels with archers, there was one of men-at-arms. He stationed some detached vessels as a reserve, full of archers, to assist and help such as might be damaged.
The English had delayed their attack until 3pm to get the high tide. They positioned themselves so the wind and sun were behind them, putting the French crossbowmen at a disadvantage. The estuary was too small for the French to manoeuvre.
Some French ships unchained themselves to pursue what were apparently retreating English ships, but it was possibly a feigned retreat (the chroniclers disagree on whether it was intended or just a lucky accident). The English had put their sails at half-mast and released their anchors, which made it look like they were about to flee. As a result, the English archers were able to target the isolated French ships pursuing them.
The heaviest English attack was directed against the Christopher, which the French had captured the previous year. Once the longbowmen had taken their first few ships, they were able to fire from the crow’s nests and rigging on to the helpless French fleet.
The sky was so thick with longbow arrows that many French sailors jumped overboard. Opposing ships would be lashed together and boarded with grappling hooks.
In the left division, the English took the Christopher, Black Cogg, St George, and St Denis among others. After the left division had been destroyed, the central division panicked and was routed even faster.
At 8pm, the Flemish finally attacked the French rear. They had been encouraged by the Bishop of Norwich and Lord Reginald de Cobham to attack in small rowing boats via the estuary’s tributaries. French sailors who managed to get to shore were clubbed to death by Flemish peasants.
According to Flemish writers at the time, most of the Norman sailors were ex-pirates who has recruited renegade Flemings. One of these, Jan van Eyle, managed to get ashore during the battle but was decapitated by a Flemish mob. Only the Flemish chroniclers attach much significance to this.
The French right division was saved only by nightfall and the exhaustion of the English.
Chaining the French ships together had been a catastrophic mistake. It destroyed any possibility of mobility and flexibility as the battle unfolded. It also impeded escape. As Froissart commented, ‘This battle was very murderous and horrible. Combats at sea are more destructive and obstinate than on land, for it is not possible to retreat and flee.’
Thomas of Burton claimed that: ‘The French left there 30,000. The sea was coloured red with blood. In many ships, men stood with blood rising above their ankles.’
His estimate of 30,000 dead might have been an exaggeration, but most historians think at least 20,000 French died – more than all the French killed at Crécy, Poitiers, and Agincourt combined.
Armoured men would have drowned quickly even in shallow water; very few medieval people knew how to swim. The French had used the ships’ lifeboats as shelters for their crossbowmen, meaning there was no means of escape remaining.
The poet Jan de Klerk wrote: ‘They were so defeated the French and they knew it so well that they leaped from the ships and with all hope lost they drowned.’
One French ship, the James of Dieppe, did not surrender until dawn the next day, by which time there were 400 dead sailors on board.
Barbavera, who had watched helplessly from the right flank, managed to escape with his squadron, which he had refused to allow to be chained with the rest of the right division.
At noon on 25 June, Edward sent 40 ships after them, commanded by John Crabbe. A few were taken, but 23 escaped, including all the galleys.
Twenty-four French ships were sunk and 166 captured. Fewer than 100 French were taken prisoner. The English lost two ships (captured by Barbavera), four knights, and about 500 men.
King Philip ordered the arrest of Barbavera and his Genoese mercenaries for treason; he would languish in prison until the next year.
Quiéret was beheaded, either during the battle or after for his killing of English prisoners at the Battle of Arnemuiden in 1338. Béhuchet was captured and brought before the King, who had him hanged from his own yardarm for his sacking of Portsmouth.
Edward was wounded in the thigh by a crossbow bolt, and stayed on the Thomas until 6 July, when it had healed.
Who was to blame for the catastrophe at Sluys? French historians blamed previous French kings for not maintaining the navy, plus the fact that few nobles agreed to command ships and that many of the sailors were actually inexperienced conscripts.
English historians have credited Edward III with building up such a fleet in so little time. Edward’s fleet had managed to get the sun, wind, and river flow behind them, while the French had thought they were retreating.
But one factor stands out above all others. Sluys was as much a triumph of the longbow as Crécy, Poitiers, and Agincourt. Indeed, with the French ships constricted by a narrow estuary and chained together, the men on board them became perfect targets for massed close-range archery.
All the same, while Sluys was an overwhelming tactical victory, it had little impact on the war in Flanders. After Edward eventually landed there, he besieged the city of Tournai, the nearest French stronghold, but failed to take it.
Sluys did have a massive impact on England, though. The first three years of the Hundred Years War have been largely forgotten, but they were a period when a French invasion of England came very close to fruition. After Sluys, while there were some French raids on the south coast for a few more months, the fighting and pillaging would otherwise all be on French soil. The north French coast was severely damaged by the loss of so many seamen.
At first, London could not believe the news of such a one-sided battle. After the reports had been confirmed, there was rejoicing. Edward even had a commemorative gold coin minted. The poet Boendale wrote: ‘May the memory of this battle in the mouth of the Zwin be kept ever green!’
The Abbot of Melsa joked that if God had given fish the power of speech they would probably speak French after eating so many of them.
The most famous anecdote about the battle comes from King Philip’s jester. Unlike Edward, Philip was not at Sluys, and no one was brave enough to tell him his fleet had been destroyed. Eventually, his jester broke the news to him:
‘Oh the cowardly English! Oh, the faint-hearted English! Our knights are much braver than the English.’ ‘How so?’ said Philip. ‘The English do not dare to jump into the sea in full armour.’ •
Edmund West is a freelance journalist with an MA in History from the University of East Anglia.
Images: WIPL/Wikimedia Commons.