Visiting Harfleur today, it is almost impossible to believe that this quiet little backwater was once one of the most important ports in northern Europe. Virtually nothing remains of the town Henry V saw on that August day in 1415; it is now merely a suburb of Le Havre, the port founded by François I in 1517 when Harfleur’s own waters silted up. The great walls that were once its pride and glory have been replaced by a labyrinthine road system of flyovers and roundabouts that are almost as impenetrable as its medieval fortifications. The salt marshes on its seaward side have became a vast industrial wasteland of smoking chimneys, oil terminals and container ports; the valley above the town, through which the river Lézarde flowed to join the Seine, is now an industrial estate and retail park linking it to Montivilliers. The lazy loops of the river itself were “redressed” by French engineers in the 1830s and replaced with rectilinear canals and quays; the fortifications that made the harbour one of the wonders of medieval Europe were demolished in the nineteenth century and the harbour itself filled in. Even the great church of St Martin, rebuilt in celebration after the English were expelled in 1435, with a delicate spire that can still be seen for miles around, is a sad and decaying historic monument for which the key literally cannot be found.

And yet the heart of the town remains defiantly picturesque: a medieval jewel lost in the swamp of Le Havre. Though Henry V’s own guns destroyed almost every building within the walls, much of the rebuilding that took place in the fifteenth century remains. Half-timbered houses crowd the narrow cobbled streets and little squares that still echo to the sound of footsteps; the more important public buildings, including the library and priory museum, though heavily restored, sport militaristic towers; and here and there, half hidden in the undergrowth, one can still find impressive vestiges of the massive walls and gates.

French contemporaries were justifiably proud of the medieval town of Harfleur. For the monk of St Denis, sheltered in his convent outside Paris, it was “the most admirable port in Normandy, sending out ships to all corners of the world and bringing back every type of foreign merchandise to provision and enrich the whole kingdom.” Enguerrand de Monstrelet, a military man, recognised its strategic importance. For him, as for Henry V, it was “the key to the sea of all Normandy.” Lying on the north bank of the tidal Seine estuary, Harfleur controlled the access to France’s most important inland waterway. Some forty miles up river, travelling as the crow flies, lay the ancient city of Rouen, where the first dukes of Normandy were buried in the tenth century and the Capetian kings of France established their royal naval yard in 1294. Around eighty miles further up river lay Paris itself, capital city, royal residence and administrative centre, with the Seine flowing through its heart. If the English could capture Harfleur, they could establish a stranglehold on military and commercial traffic using the Seine and block one of the main arteries of France.

There was a second strategic purpose to be achieved in capturing the town. Of all the places on the northern coast of France, Harfleur posed the greatest threat to English interests. In recent years it had become the base of choice for attacking the south coast of England: Don Pero Niño, the “unconquered knight,” had retreated to its safety with his prisoners and plunder after raiding the coast of Cornwall in 1400, and Louis d’Orléans had gathered an invasion fleet there in 1404. French troops sent to aid Owain Glyn Dŵr’s revolt in Wales and the Scots in their campaigns against the English had all sailed from Harfleur. In England the town had also acquired the reputation of being a nest of pirates: many of the attacks on merchant shipping in the Channel had been carried out by French and Italian vessels which took refuge within its harbour and found a ready market for their prizes there. For all these reasons, Henry V had identified Harfleur as the target for his invasion. Its capture would serve a dual purpose, increasing the safety and security of English shipping and establishing another bridgehead, like Calais, for any future campaign in France.

Harfleur’s strategic importance had ensured that it enjoyed the best protection that medieval military might could devise. Great stone walls, some two and a half miles in circumference and fortified at intervals with twenty-four watch towers, encircled the whole town and its famous harbour. These were relatively modern fortifications, built between 1344 and 1361, and the plan was polygonal, with semicircular flanking towers at each angle, which were harder to demolish by cannonade or undermining than traditional square towers. The walls themselves were thicker at their base than at the top, sloping outwards so as to deflect shots from guns and catapults back into the enemy, and the many towers provided vantage points from which flanking fire could be rained on anyone approaching the walls. There were only three gates, guarding the entrances into the town from Montivilliers to the north, Rouen to the south-east and Leure to the south-west. A remnant of one of the towers at the Rouen gate, which also commanded the harbour, or clos-aux-galées as it was known to the French, is the sole survivor today. Though a ruin, its former might is still readily apparent in the depth of its great stone walls, strengthened by arches inside, the absence of any flat external surface and the many small embrasures, at varying heights, for crossbows and guns. Each of the three gates was protected by a bastion (a fortification projecting beyond the line of the walls), a portcullis and a drawbridge over a water-filled moat; these permanent defences had also been strengthened against missile attack by thick tree trunks, driven into the ground and lashed together on the outside, and earth and timber shoring up the walls on the inside.

The defence of Harfleur had been entrusted by Charles VI to Jean, sire d’Estouteville, who held the honorary office of grand butler of France. He had with him a garrison of some one hundred men-at-arms, which, even with civilian assistance, was not a large enough force to be able to offer any prolonged resistance to a determined English assault. Nevertheless, all the natural advantages of the site had been exploited to the full. The town lay about a mile from the Seine, at the head of the tributary valley of the river Lézarde. The southern approach was protected by the ebb and flow of the Seine tides over treacherous salt marshes. The waters of the Lézarde, which entered Harfleur midway between the gates of Leure and Montivilliers, had been partially diverted along a series of ditches and culverts to create a great moat which encircled more than half the town, from the north-east to the south-west, and defended it against attack from the upper reaches of the valley. Controlled by sluices, the river waters powered two mills for grinding corn, which lay just within the walls, and then flowed down a series of culverts through the middle of the town before broadening out to form the harbour and joining the Seine. The great advantage of these sluices from a defence point of view was that they could be closed completely. When this happened, the Lézarde was effectively dammed at its entrance to the town and therefore burst its banks, flooding the entire valley bottom to the depth of a man’s thighs. Forewarned that the English were landing close by, the men of Harfleur broke all the bridges across the river and closed the sluices, creating a vast lake to protect the northern side of the town.

The clos-aux-galées was probably even more strongly fortified than the town. It was created in the 1360s by constructing a massive wall, more than six and a half feet thick and standing fifty feet high above ground and thirty-six feet below, around a loop in the Lézarde to the south of the town. This was then flooded to create a twelve-acre harbour that was both commercial port and royal military arsenal. Protected to the north by the town walls and on either side by its own higher wall, surmounted by defensive turrets, its seaward entrance was guarded by two massive towers, with chains strung between them to prevent unauthorised access. When the English invasion threatened, the French had taken emergency measures to provide additional defences, planting great sharpened stakes around the entrance and under the walls facing the sea, so that, when the tide was up and enemy ships could sail right up to the walls to launch an attack, they ran the risk of being driven onto the stakes and foundering.

The story of the siege of Harfleur might have been very different had it not been for the courage and resourcefulness of one man. Raoul, sire de Gaucourt, was a French version of Sir John Cornewaille, and, like him, a medieval chivalric hero whom the modern world has forgotten. He came from a noble Picard family with a long and distinguished record of service to the crown. Like his father before him, he was deeply attached to the Armagnac cause and had strong personal connections with Charles d’Orléans, Charles d’Albret and Marshal Boucicaut. More importantly, de Gaucourt was a man who aspired to live out the knightly ideal. He was knighted on the field of Nicopolis as a twenty-six-year-old crusader against the Turks, and, with Boucicaut, was captured and put to ransom in that disastrous battle. In 1400 he was one of the fourteen founding members of Boucicaut’s short-lived knightly Order of the White Lady on a Green Shield, who swore “to guard and defend the honour, estate, goods, reputation and praise of all ladies and maidens of noble line” and to fight à outrance against their oppressors. Nine years later, when Boucicaut was governor of Genoa, de Gaucourt led a small French army to his assistance. The two men campaigned together in Italy throughout the summer of 1409, besieging and capturing Milan, and when Boucicaut made his triumphal entry into the city, de Gaucourt was at his side. In the armed struggle between the Armagnacs and the Burgundians, de Gaucourt distinguished himself in 1411 by capturing the bridge of St Cloud on behalf of Charles d’Orléans, but was later defeated in battle at the same place by a combined English and Burgundian force. As the chamberlain of Charles d’Orléans, he played a prominent role in the negotiations that led to the withdrawal of the duke of Clarence’s army from France in 1412 and served as captain of several Armagnac castles.

On 1 January 1415, de Gaucourt was one of sixteen knights and esquires who were chosen by Jean, duke of Bourbon, to be the founding members of another new order of chivalry, the Order of the Fer du Prisonnier, or Prisoner’s Shackle. Like Boucicaut’s order, the duke of Bourbon’s was intended to uphold the honour of women of good birth: the golden shackle, with its chain, being a symbolic representation of the bonds of love, which fettered the knight to his mistress, rather than a reference to criminal activity. In accordance with the order’s constitution, de Gaucourt swore to wear a golden shackle and chain on his left leg every Sunday for two years, “in the expectation that, within that period, we may find an equal number of knights and esquires, of worth and ability, all of them men without reproach, who will wish to fight us all together on foot to the end, each to be armed with what armour he will, together with a lance, axe, sword and dagger at least, and with clubs of whatever length he may choose.” The arms of all the members of the order were to be hung in a chapel where, throughout the two years, a candle would burn, day and night, within another golden shackle used as a candlestick, before an image of Our Lady of Paris. If the challenge was accomplished, then the candle was to be endowed in perpetuity, together with daily masses, and each member would donate to the chapel his shackle and a picture of himself in the arms he wore that day. Anyone who forgot to wear the shackle on the designated Sundays had to pay a fine of four hundred shillings to charity for each offence.

De Gaucourt’s membership of this order raises the interesting possibility that he was wearing his golden shackle on Sunday 18 August, as he performed the far more serious challenge of leading three hundred men-at-arms to the relief of Harfleur. Constable d’Albret and Marshal Boucicaut had not been entirely idle during the English landing. As soon as it became clear that Harfleur was Henry V’s objective, they sent a stream of supplies, including weapons, cannon and ammunition, to reinforce the town. They must also have decided that they needed an experienced and trustworthy knight to take charge of the defences, which is why Raoul de Gaucourt was chosen for the task. Whether he came from Honfleur or Caudebec, the only route he could take into the town was through the Rouen gate on the eastern side. Time was of the essence. He had to get there before the English. His arrival, only the day after Henry laid siege to the western side of Harfleur, is an indication of the desperate pace of his dash across Normandy. Fortunately for his mission, the flooded fields that denied him access to Harfleur from the Montivilliers road also protected him, for the moment, from the English troops encamped on the hillside before the Leure gate. They could only watch helplessly as de Gaucourt coolly rode unopposed down the other side of the valley and into the town. It was not often that Henry V was outmanoeuvred and, as de Gaucourt was to discover to his cost, the king was not a man to forgive or forget such actions.

Henry’s inability to prevent de Gaucourt and his men getting into Harfleur demonstrated that it was imperative that no further reinforcements should reach the town by the Rouen road. He now entrusted this important task to his brother the duke of Clarence, whom the chaplain described as “a knight no less renowned for the practice of war than for personal courage.” In this instance, he proved himself worthy of both Henry’s confidence and the chaplain’s praise. Under cover of night, he led a large force of men and an artillery train on a difficult ten-mile detour that took them above, up and around the flooded Lézarde valley. During their march they even managed to intercept more reinforcements arriving from Rouen and captured “certain carts and wagons belonging to the enemy, with a great quantity of guns and powder-barrels and missiles and catapults.” At dawn the following day, to the consternation of the besieged, Clarence and his men appeared on the opposite hillside above the town, facing Henry and his troops.

While all these preparations were being made to lay siege to Harfleur by land, the seaward side was not neglected. Most of the merchant ships that had transported the army to France were allowed to go home after completing their disembarkation, though some returned again, bearing further supplies and reinforcements, including the men who had been left behind when the fleet first sailed. The fighting ships and the royal fleet were not released from service but moved in to blockade Harfleur, barring all access from the Seine or the sea; a number of small boats, carried overland and taking up position on the flooded Lézarde, did the same from the north. Trapped between the two armies to west and east, and blockaded by water to north and south, Harfleur was now completely encircled.

Before the great guns began their bombardment, Henry, punctilious as ever, gave the people of the town one last chance to surrender. He sent one of his heralds to proclaim that in accordance with the twentieth chapter of the book of Deuteronomy (which Henry had already quoted to Charles VI in his letter of 28 July), he offered them peace—if they would open their gates to him freely and without coercion, and, “as was their duty,” restore to him the town, “which was a noble and hereditary portion of his crown of England and of his duchy of Normandy.” If this offer was refused and Harfleur was captured by force, Deuteronomy authorised Henry to exact a terrible vengeance: “you shall put all its males to the sword, but the women and the little ones, the cattle, and every thing else in the city, all its spoil, you shall take as booty for yourselves; and you shall enjoy the spoil of your enemies, which the Lord your God has given you.” Though de Gaucourt and d’Estouteville knew as well as Henry what the consequences of their refusal to surrender would be, their duty and honour would not allow them to do anything other than reject his offer out of hand, and defy him to do his worst.