Skip to content
Home » Articles » Henry V: The Invasion of France

Henry V: The Invasion of France

Portrait of Henry V

On 13th August 1415 a large fleet of English ships landed near Harfleur in Normandy.  The fleet was carrying Henry V and his army.  His stated purpose was to claim the French throne.

After an uneasy hiatus of 26 years, The Hundred Years’ War erupted anew.  It was the start of a campaign that would reach a climax with Henry V’s historic victory at Agincourt. 

This is the story of how that campaign developed and the events that led up to the historic confrontation at Agincourt.

Henry prepares

Mounting a campaign as ambitious as the conquest of France required a lot of careful planning and preparation.  By the time Henry V became king in 1413 he was already an experienced military commander.  He’d fought a long and difficult campaign against Welsh rebels during his father’s reign.  Despite his best efforts, he’d often found himself hampered by inadequate financing and a lack of resources.  He’d also seen how rebellions and dissent elsewhere in the kingdom hampered efforts to defeat the Welsh rebels.

As a result, Henry understood all too well that for any war in France to stand any chance of success, the kingdom had to be stable and the campaign well-funded.

Henry determined not to repeat the mistakes of his father’s time.

Royal authority

Henry invested considerable energy in ensuring his nobility were fully onboard with his plans.  He used the first two years of his reign to clamp down hard on any dissent and make it crystal clear that he, and he alone, was in charge.  Rebellion or even a hint of rebellion, whether from Lollards or disenchanted nobles, was ruthlessly crushed.  Whilst Henry was willing to show some mercy, any ring leaders (or even suspected ring leaders) always faced death.  There were no exceptions, as Richard of York’s father found out to his cost.

When two lords fell out and started raising men to settle their differences by military means, Henry was not amused.  He summoned them both to attend him.  He asked them whose subjects they were currently calling to arms.  Both had no option but to agree that these men were the king’s subjects.  Henry told them he forbade his subjects to fight each other.  As he sat down to a meal, he coldly informed the pair that unless they settled their differences by the time he finished eating, they’d both hang. 

By 1415 everyone in England was in no doubt – cross Henry V at your peril.


France in 1415 was undeniably vulnerable.  The French king, Charles VI, was incapacitated with mental illness.  His heir, Dauphin Louis of Guyenne, was an inexperienced youth with limited political and military aptitude.  Worst of all, the French court was split between two rival factions that hated each other.  The Armagnacs led by the Duke of Orleans, and the Burgundians led by the Duke of Burgundy.  They had been fighting a bitter, on-again, off-again civil war ever since 1407. 

Portrait of Charles VI of France
Charles VI of France.  He suffered from severe psychosis from his mid-twenties.  On one occasion he was unable to recall his own name, failed to recognise his wife and was not aware of the fact that he was the king.

By 1415 it was the Armagnacs who controlled the court.  And although an uneasy truce existed between the two factions, most people expected it to break down at any time.

Nevertheless, France still had the potential to call on far greater resources than England.  Henry V set about laying the diplomatic groundwork to ensure France would receive no aid from potential allies in places like Spain.  He also worked hard to ensure enemies of the Armagnacs, such as Burgundy, would remain reasonably neutral whilst he fought his war with the Armagnac court.


Medieval war was very expensive, and Henry was all too aware of how difficult it was to fight a war with limited financing.  He therefore put considerable energy into getting royal finances in order, trimming costs where he could and seeking to optimise revenues.

Henry was a meticulous workaholic who, unlike many other medieval kings, took a very close interest in finances.  He personally poured through accounts, adding notes and questions in his own hand for further investigation.

Whilst Henry enjoyed some success in balancing the royal accounts (probably exaggerated by the Chroniclers of the time), it was not enough to adequately finance a war.  For this Henry required parliament to raise special direct taxes, but even this was not enough.  Henry had no option but to borrow money from wealthy individuals like Sir Richard Whittington and his own uncle, Bishop Henry Beaufort.

Financing such an ambitious undertaking was a real stretch but, in the short term at least, the Lancastrian regime was able to manage.


In all Henry was able to assemble an army of 12,000 men and some 20,000 horses for the invasion.  He also brought a significant artillery train with him.  These guns were cumbersome, unreliable, had a slow rate of fire, and only able to fire stone shot.  They were largely impractical for use in a pitched battle.  However, by the early C15th they were invaluable in a siege, being more effective than traditional siege weapons such as trebuchets and mangonels.

Much to Henry’s relief, his invasion fleet landed unopposed on 13th August 1415.  This was a piece of luck since the French had prepared strong coastal defences in the area.  Fortunately, these were unmanned.  This omission caused something of a scandal at the French court.  However, it was undoubtedly a reflection of the limited resources available in the area at the time.  The French military command knew Henry was on his way but had no way of knowing where he would land.  There simply wasn’t the manpower to adequately defend the entire coast.

Having successfully landed, Henry’s priority was to secure the nearby port of Harfleur.  He would then be able to use this as a base for future operations. 


As he approached the port, Henry issued the defenders with an ominous ultimatum.  Claiming to be their rightful king, he demanded they surrender the port to him.  He then quoted the book of Deuteronomy as to the dire consequences if the town should choose to disobey:

“And if it will make no peace with thee, but will make war against thee, then thou shalt besiege it:

And when the Lord thy God hath delivered it into thine hands, thou shalt smite every male thereof with the edge of the sword:

But the women, and the little ones, and the cattle, and all that is in the city, even all the spoil thereof, shalt thou take unto thyself; and thou shalt eat the spoil of thine enemies, which the Lord thy God hath given thee.”

Deuteronomy 20, 12-14

Henry’s use of Biblical threats stemmed from an unshakeable belief that it was God’s will that he should be king of France.  It was his divinely ordained destiny.  His cause was not only just but sanctioned by God.

Harfleur was only defended by a small garrison commanded by Jean d’Estouteville.  Although the defences were strong, d’Estouteville had a mere hundred men-at-arms at his disposal.  Nevertheless, he was not willing to submit to Henry’s ultimatum.

Relief force

The main French military command was based some considerable distance away at Rouen.  And any significant help from there seemed very unlikely to arrive anytime soon.  Nevertheless, a small relief force of 300 men-at-arms commanded by the dashing Raoul de Gaucourt attempted to make it to Harfleur to reinforce the garrison.

Harfleur had three main gates, on the roads heading south-east to Rouen, north to Montivilliers and south-west to Leure.  Henry approached from the west.  To prevent him from easily encircling the city, the defenders closed sluice gates on the river Lézard.  This had the effect of flooding the salt marshes to the north of the town, creating a large lake outside the northern walls.

In the initial instance, the English army was only able to lay siege to the south-western Leure gate.  Raoul de Gaucourt approaching the Rouen gate on the other side of the Seine estuary, was able to enter the city unopposed.  Henry’s army, stuck on the other side of the estuary, could only watch in frustration.  If de Gaucourt had arrived even a day later, he would have been too late as by that time, Henry’s army had fully invested the town.

By 18th August, the town was full besieged.

Harfleur besieged

Henry quickly deployed his artillery, tasking them with bombarding the defences all day, every day, resting only at nightfall.  A total of twelve cannons and several more traditional siege engines maintained a constant bombardment.  According to one French Chronicler (the so-called ‘Monk of St Denis’), one of these cannons was the largest anyone had ever seen.  It fired huge cannon balls the size of millstones.  And when it fired, there was a thunderous boom accompanied by so much black smoke that “they seemed to issue forth from the fires of hell”.

Map of Henry's siege of Harfleur
The siege of Harfleur began on 18th August 1415.  Henry originally felt he could take the town quickly, but in the end, it held out for a month.

The defenders desperately attempted to effect makeshift repairs each night to delay the inevitable.  And yet, slowly but surely, the defences were reduced.  The damage within the town was horrendous.  Many of the residences were smashed to rubble and splintered wood by the continuous pounding.

Henry had to split his forces in two to invest the two useable town gates (the northern gate was unusable due to the flooded fields beyond).  He sent his brother, Thomas, Duke of Clarence, to command the men attacking the Rouen gate on the other side of the estuary.  Meanwhile he personally supervised the forces besieging the Leure gate.

Battle beneath the earth

A common tactic in medieval sieges was to dig a mine under the walls, set fire to the wooden supports, causing the wall to collapse.  This the English attempted to do on the Rouen side of the town.  Ideally a mine should be dug out of sight of the defenders.  This was because, if they could see where it was being dug, they could dig a counter-mine.  The aim of a counter-mine being to dig beneath the enemy’s tunnel and collapse it before they reached your walls.

Unable to conceal the mining activities from the French, Clarence’s miners constantly found themselves under mined.  Occasionally, the opposing mines would meet, resulting a desperate sub-terranean skirmish.

The result was a fiercely fought underground stalemate.

Clarence’s assault

The walls around the south-eastern approach were further defended by two rings of defensive ditches, dug outside the walls.  To get close enough to the walls to properly engage the defenders required bridging at least one and ideally both.  And so, Clarence had his men prepare bundles of wood, which they could use to quickly fill the ditches, enabling the attackers to cross.

The French, however, were one step ahead of the game.  As Clarence’s men began their assault, the French poured oil and other inflammable material over the wooden bundles.  Then they torched them, engulfing the attackers in flames as they attempted to cross.

Despite this Clarence pressed home the assault and finally secured the outer ditch.  His men were now close enough to the walls to engage the defenders with arrows and guns, forcing them to take cover, making it far harder for the French to observe his actions.


Eventually Henry damned the river, draining the fields and making it easier to fully invest the town.  This also had the effect of cutting the town off from its only supply of fresh water.

However, as the siege wore on, an epidemic of dysentery broke out in the English camp.  This was first noted on 15th September.  It wasn’t long before it began taking a heavy toll on the attackers.  The disease easily killed more men than were dying in the fighting.  It also debilitated many others for days, even weeks and, even though they may not have died, they were certainly unfit for fighting.

In time dysentery spread to within the town as well, striking down many of the defenders.

All the while de Gaucourt was desperately sending messages to the French court calling for aid.  His ability to communicate with Rouen was naturally limited.  However, a cunning French sailor by the name of Jehan Lescot managed to evade the blockade twice, bring in invaluable supplies and convey messages.

Despite de Gaucourt’s desperate pleas, no help came. 

The final assault

On the night of 15th September, a small French raiding party led a daring assault, sallying forth from the Leure gate.  They caught the English off guard and, after a fierce skirmish, managed to set fire to some of the English defences.  The raiders had taken casualties and their attack achieved little, but it was a valuable morale boost for the defenders.

Henry's final assault on Harfleur
The final assault and the lack of help from Rouen prompted the town to surrender.

On 16th September Henry responded by launching a major assault on the Leure gate.  The fighting was fierce and went on late into the night.  The English set fire to the outer bastion, forcing the French to abandon it and retire back inside the town walls.

On the 17th, Henry made one last appeal to the town to surrender or face dire consequences.  The final assault was just beginning on the morning of the 18th when a deputation of town Burgesses came to Henry offering terms.

They asked to be allowed to send one last message to Rouen, asking for aid.  If no relief force had arrived by the 22nd, they agreed to surrender the town to Henry on that day.

A final message was sent.  No aid came.  The siege was over.

The fall of Harfleur

Thanks to de Gaucourt’s efforts, Harfleur held out until 22nd September.  He had only finally agreed to surrender when it became clear that no French relief force was coming.

Henry finally took the port.  However, the cost had been high.  The debilitating epidemic of dysentery meant that many soldiers had either died or had to be invalided home.

As for Harfleur itself, the siege had taken a great toll.  Most of its residences had been damaged or destroyed and dysentery had taken a similarly heavy toll on its unfortunate citizens.

Henry V chose to let de Gaucourt go free so that he could carry a message to the Dauphin.  In it Henry challenged the Dauphin to settle their differences in a trial by single combat.  Henry of course knew that the Dauphin would almost certainly refuse.  However, he calculated that the loss of face this entailed would damage French morale.

What remained of Harfleur’s richer residents were given a choice.  They could either swear allegiance to Henry or face imprisonment until such time as they could be ransomed.  The poorer residents and the sick were ruthlessly evicted, their property forfeit.  This may seem harsh but in medieval terms it was viewed as surprisingly merciful.

French Response

But why had the French not come to Harfleur’s aid?  The port did not fall until 22nd September, over a month after the English first landed.

The truth was that the situation was complicated.  Sure enough, it would take time to assemble the full force of the French army.  However, there remained the problem of the ongoing Armagnac-Burgundian feud. 

The court was, by this time, mostly dominated by the Armagnac faction.  Raising forces from this source was relatively straightforward.  The Burgundian faction was another story.  No one was quite sure what the Duke of Burgundy’s position would be.  Would he come to aid the crown against the English?  Would he stand aside and watch whilst the Armagnacs and the English slogged it out?  Perhaps he even had some secret arrangement with the English?  Did Henry and the Duke plan to carve up France between them?  There was no way to be sure.  Confronting the English whilst the position of Burgundy remained so unclear was dangerous.

The court summoned French forces from both factions.  But even this carried dangers.  The Dukes of Orleans and Burgundy hated each other with such venom that they were as likely to attack each other as join to fight the English.  Both Dukes were therefore ordered to send their forces but to personally stay away.  Burgundy stayed away but sent very little aid.  Orleans sent considerable aid and showed up in person.

French Leadership

The issue of who would lead the French army was problematic.  King Charles VI’s poor mental health meant that it could not be him.  The Dauphin, at eighteen, had no military experience to speak of and showed little interest in military matters.  His refusal to answer Henry V’s challenge to trial by single combat placed a further question mark over his suitability.  For these reasons, and out of concern for his personal safety, he would not lead the army.

Military leadership therefore fell, in theory, mainly to two men.  The first, Marshal Boucicaut was an experienced soldier.  He had an impeccable reputation as a brave soldier but a rather patchy career as a commander.  Then there was Charles d’Albret, the Constable of France, another experienced soldier.  Both enjoyed high office but lacked high noble rank.  This was unfortunate.

Also present in the army were several Dukes: notably, the Dukes of Orleans, Bourbon and Alençon.  Socially and politically, they outranked the military commanders to a significant degree.  This was especially true of the Duke of Orleans, leader of the Armagnac faction that dominated the court. 

Key decisions therefore had to be taken by a council rather than by any one man.

It was a far from ideal situation.


Henry V now had some tough decisions to make.  It had taken longer than planned to secure Harfleur.  Autumn was wearing on and dysentery had taken its toll on his army.  He could have returned to England by sea and waited until spring before making his next move.  However, he chose not to do this.

Instead, he chose to march eastward, across northern France, to Calais.  This seemed a little foolhardy to some of his councillors given the time of year and condition of the army.  Clarence was prominent amongst those arguing in favour of a return to England by sea.  The army, he argued, could then return in the next campaigning season and renew their efforts, fresh and fully resupplied.

Henry overruled any such objections.  Clarence was sent back to England, ostensibly to recover from dysentery, although it may have been to remove him from the chain of command.

Henry was so sure of himself that he was confident that, even in a pitched battle with a larger French force, he would still win.  The march was also a provocative statement of intent.  In Henry’s mind, he was marching through ‘his’ lands, as he had an absolute right to do.  It would serve as a very public demonstration of his royal power over the French.

And so, taking what was thought to be adequate supplies for the march, the army set off from Harfleur for Calais in early October.

The March to Calais

Henry was determined that the march would be a disciplined one.  Previously, English armies in France had behaved exactly like foreign raiders.  They typically adopted an approach known as the chevauchée, moving at speed, pillaging, and burning everything in their path.

Now Henry wished to send a message that he was serious about being king of France.  Therefore, the French were to be treated as his subjects.  Strict instructions were issued to the army forbidding pillage, rape, and other crimes.   Henry would not allow his army to mistreat the local population unless and until he decided it was necessary.  As usual Henry was true to his word, hanging one soldier who had dared to steal from a French church.

When encountering a town whose defences threatened to bar his way, Henry did not demand its submission.  Instead, he either bypassed it or, if that were not possible, he threatened to devastate the surrounding countryside unless he was granted free passage and supplies.  Fortunately for the French commoners, local garrisons acquiesced to these demands as Henry marched eastwards across northern France.

A game of cat and mouse

By early October the French were finally ready.  They soon worked out that Henry was probably heading for Calais and moved to deny him passage across the Somme. 

There followed a cat and mouse game that lasted several days.  Henry attempted to find a crossing only to find it blocked by the French.  He marched further south only to find his way blocked again.  Henry’s army now began running out of food.  Things were not looking good.

Finally, Henry took a gamble.  He bypassed a bend in the river, travelling inland so that the French on the other side of the river couldn’t follow his movements.    It paid off.  He re-joined the river farther to the south near the French town of Nesle.

Map of Henry's march towards Agincourt
The road to Agincourt

Here he found the town fortified against him and passage denied.  He made his usual demands for supplies and passage in exchange for passing by peacefully.  However, this time the local garrison took a stand, denying him both. 

Henry prepared orders for his men to burn and pillage the surrounding hamlets as punishment.  However, in the end the locals were spared because Henry discovered a fordable, unguarded, crossing nearby.  The was no time to waste.

The English army crossed the Somme on 19th October. 

The road to Agincourt

Although Henry had finally managed to cross the Somme, the French army still stood between him and Calais.  With his dysentery-ridden army running low on supplies, he had no option but to press on.  It now seemed inevitable that he would have to do battle at some point, it was only a matter of time.

Sure enough, it wasn’t long before a French messenger appeared at the English camp.  He carried with him a challenge to do battle.  Henry responded that, since his army marched openly through France, the French were free to do battle with him whenever they chose.

On 24th October, somewhere near the French town of St Pol, Henry’s scouts returned with the news he’d been expecting for a few days.  They had spotted the French army.  It was just three miles away and there were many thousands of them.  It was a force that clearly outnumbered Henry’s army by a significant amount.

Later that day, the English found the road ahead blocked.  The French army was assembled before them in full battle array, sitting between them and Calais.  Battle was now inevitable.  It would be fought in the fields next to a small nearby French village called Agincourt.

Next time…

The next article in this series will cover the battle of Agincourt, Henry’s most famous victory.  It will be published on this blog in early December.

Keep up to date with our stories

If you like reading our work and would like to keep up to date with the latest stories and news from our blog page, you can follow us on Facebook.  We always announce any news and promote new stories as they are published here:

If you would like to read my articles on other medieval English kings…

The making of Henry V

Henry IV (in order):

Adventures of Young Henry of Bolingbroke

The Elected King

Founding of a Dynasty

Richard II (in order):

Boy king


The legacy of Richard II

References & further reading:

Agincourt:  The king, The Campaign, The Battle. Juliet Barker. Abacus. 2006

A baptism of fire, steel and stone: Henry V’s army and the siege of Harfleur, Benjamin Trowbridge

Siege of Harfleur – Wikipedia


Portrait of King Henry V – from the National Portrait Gallery, anon C16th (from wiki commons)

Portrait of King Charles VI – from Dialogues de Pierre Salmon (Bib de Genève MsFr165f4), photo by de Vecchi-Cerchiari.  (From wiki commons)

Siege of Harfleur map created by Paul Watts

Siege of Harfleur 1415 illustration by Thomas Grieve 1859 (from wiki commons)

Agincourt campaign map created by Paul Watts based on a map of Northern France and Flanders in 1383 by Hel-Hama (originally from wiki commons)

Leave a Reply

Your email address will not be published. Required fields are marked *