22 October 2015

Agincourt or Azincourt?
Victory, Defeat and the War of 1415

Dr Helen Castor

I would like to begin this evening with a brief glimpse of a book that seems to be exactly the kind of historical digest we have all been waiting for. HISTORY'S GREATEST HITS, it is called: Famous events we should all know more about. The premise of that stern subtitle is probably unarguable; there are certainly plenty of famous events I, for one, should know a great deal more about. But my particular reason for starting with this book today is that it raises the question of what exactly history's 'greatest hits' are, and how they might be chosen.

Let us take a look at what the contents page offers us from the five hundred years of the Middle Ages and Renaissance. It is a select bunch, starting with 1066 and the battle of Hastings, moving swiftly through the Crusades and past Magna Carta in 1215 before encountering the Black Death in the mid-fourteenth century. And then, right in the middle of the list, comes 1415 and the battle of Agincourt.

Agincourt, if we look closely, is one of only two battles that make it into this medieval hit parade. The first, Hastings, was the last successful invasion of England – a battle that changed the course of this country's history for ever. The second, Agincourt, did not. So why is it there?

The answer, in one word, is Shakespeare.

In the English-speaking world – and we know we are in the English-speaking world because on this list is 1431, the execution of Joan of Arc, not 1429, the victories of Joan of Arc, which would be the more likely French selection – Shakespeare's play Henry V, written in 1599, has fixed this battle in our collective imagination, inserted it into our cultural DNA.

And that is not just because of Shakespeare's genius with words, though there is plenty of that on display in Henry V. As the play moves from 'O for a muse of fire…' via 'Once more unto the breach, dear friends' all the way to 'We few, we happy few, we band of brothers', it is packed with gorgeous lines.

But it is also a play with an almost mythical narrative arc. A young man – a young king, newly come to his throne – is determined, after a misspent youth, to live up to the weight of dignity and responsibility he has now inherited. An ancient enemy does not take him seriously. (You may remember that at the very beginning of the play, the French send a gift to suit his temperament: 'Tennis balls, my liege' is a line that somehow always pairs itself with Lady Bracknell's 'A handbag?' in my theatrical memory.)

But this young king has charisma, integrity, moral purpose and a vision of his country's destiny. He launches a great invasion of the kingdom across the sea which he claims as his. He takes the port of Harfleur, and marches on, only to be confronted by the might of the French army, an army made up of huge numbers and led by the princes of the blood who – with supreme disdain and condescension – assume victory is rightfully and naturally theirs before a blow is struck. (Another wonderful scene, the night before the battle, opens with the Constable of France declaring languidly, 'I have the best armour of the world!)

Back in the English ranks, on the eve of battle Henry confronts a long dark night of the soul, and comforts his men with a 'little touch of Harry in the night'. But then, when battle is joined, this turns out to be the tale of David and Goliath. The proud and arrogant French are brought down, against all the odds, by the courage and heart, the resilience and endurance of the English army. And then, after this astonishing triumph, this moment of catharsis, at the end of the play Henry receives his just reward: the hand of a French princess – sweetly wooed across the divide of language – and is recognised as heir to the French throne.

But of course, glorious as it is, this is a drama. And what I want to do today is to take a closer look at what we think we know about Agincourt, to consider whether the way we think about the battle is an accurate reflection of fifteenth-century reality; and to ask – Shakespeare aside – does it really deserve its place among history's 'greatest hits'?

I ought to make clear first of all that I am not, in the specialist sense, a military historian; but of course it is impossible to write about any period of human history without writing at some stage about war. And in tackling the subject of my most recent book – Joan of Arc, the most famous female soldier ever – not only was war inescapable as the defining context of her life and her brutal death, but, when I came to write, it was Agincourt that presented itself as my starting-point.

In doing so, my focus was not principally on troop movements and topography, battle plans and tactics – and not just because of my own lack of expertise, but also because, in dealing with the middle ages, those neat diagrams with rectangular blocs moving across battlefields under the leadership of large black arrows can be significantly misleading, in a context where it can be tricky even to establish how many soldiers fought on each side to the nearest couple of thousand, let alone where they stood and exactly what they did.

Instead, what fascinates me is the psychology and the politics of war. So what I am going to start with, in talking about Agincourt today, is not the battlefield: it is the naming of things. The labels we attach to the past shape the way we think about history, and they do it so profoundly that we need to keep a close eye on what that process does to our understanding.

Let us think for a moment even about the name of this battle: we call it Agincourt, but there is no such place on the French map. Over there, it is Azincourt – and a large part of what I want to talk about today is the French experience of the dreadful defeat of Azincourt, rather than the victory of the happy few at Agincourt. Straight away, it is clear that we might be dealing with two different stories, depending on where we stand to view the fighting. But Agincourt – or Azincourt, either way – forms part of a grander narrative, one that also deserves our attention for a moment: the narrative of the Hundred Years' War.

If we want to understand the past, we have to understand how our protagonists saw themselves and the world in which they lived. We need to understand the choices they faced as seen through their eyes, knowing only what they knew when they formed their judgements and made their decisions, because once hindsight comes into play, we are no longer understanding the past in its own terms.

The Hundred Years' War is a good example of why that matters. It only takes a moment, once we stop ourselves to think, to realise that those who fought in it had no idea it was the Hundred Years' War they were fighting. For them, it was not over till it was over, and they did not know when that would turn out to be. In fact, it is a term first coined in the nineteenth century, like so many of the other neat and evocative formulations we use about our medieval past – the 'Wars of the Roses' being another, although the 'Hundred Years' War', unlike the 'Wars of the Roses', was first coined in French, as 'La Guerre de Cent Ans'. The first usage recorded in the Oxford English Dictionary is from 1874, by J.R. Green in his Short History of the English People. In 1453, he declares, 'The Hundred Years' War … ended'.

What Green (and the others who first used the term) was suggesting was that the many phases of conflict between England and France that took place between 1337 and 1453 – so, a period of 116 years, rather than a round 100 – had a unifying principle, a connecting cause; and that cause was the English claim to the French throne first made by Edward III in right of his French mother Isabella, daughter of Philip IV of France. This was a claim that Edward and the English kings who succeeded him tried to make good by military means until the moment in 1453 when all English lands in France were finally lost, bar the fortified town of Calais, which lasted one more century until the French recaptured it in 1558. So, put like that, it is entirely possible to see the case for treating this century of conflict as a whole, or at least as having some kind of continuity at its core.

But if we look a little more closely, the picture gets more complicated. Kings of England had held territory in France ever since the Conquest of 1066. They held the Conqueror's own duchy of Normandy, until it was lost by King John in 1204; but by then the English also held the duchy of Aquitaine in south-western France that had been brought to the crown by John's mother, Eleanor of Aquitaine, when she married Henry II in the middle of the twelfth century. The extent of this territory, and the terms by which kings of England held it from the kings of France, had given rise to war between the two kingdoms for significant stretches of the two centuries before 1337. So by 1337, war between England and France over the rival territorial and tenurial claims of the two monarchs already had deep roots and a long history.

It is true that an English claim to the French throne had not been part of that previous conflict; but it is debatable whether the assertion of that claim was a radical reformulation of the conflict between the two sides, or whether it was just another string to the English king's bow. Edward III, whose claim it was, gave it up in 1360 – only a quarter of the way through the hundred years of the Hundred Years' War – as part of the terms of a treaty I will tell you about in a moment. It was then revived by his successors – but 1453 did not mark the end of the claim. Henry VIII, for one, was still serious about prosecuting it when he took an army to France in the early sixteenth century; and it was not finally given up and dropped from the English royal title until 1801. All of which suggests that we might need to take a closer look at the shape of events between 1337 and 1453 if we are going to get a real sense of what was happening in France in the early decades of the fifteenth century, and specifically in 1415.

It is important to recognise that warfare was not constant between 1337 and 1453, either in form, or in the very fact of there being fighting at all. Edward III, for example, won great successes – at sea at Sluys in 1340, at Crécy in 1346, and at Poitiers in 1356, when the French king himself was captured. But in 1360, as I have said, Edward gave up his claim to the French throne as part of the Treaty of Brétigny, in return for holding the territories of Aquitaine, Poitou, Ponthieu, Guînes and Calais, not as a vassal of the French crown any longer, but now in full sovereignty. Then there was peace for nine years; then war resumed – because of French determination to overthrow the terms of the treaty – for twenty years from 1369 until 1389, when a temporary truce was agreed, followed seven years later by an agreement for a further truce, which was intended to last for twenty-eight years.

So here, in the last decade of the fourteenth century, was a period of peace between England and France in which the whole ostensible project of the war – the English claim to the French throne – was, if not yet settled, at least in abeyance. And here, therefore, is where we need to look more closely at exactly how events unfolded on both sides of the Channel. How and why did the armies of England and France come to face each other on the field at Azincourt on 25 October 1415?

The answer is that both kingdoms were plunged into periods of devastating turmoil, but with very different results. In England, peace with France had been pursued by Edward III's grandson, Richard II – the son of the Black Prince, who had none of his father's military ambition or talent. Instead, Richard saw a much greater enemy facing his sovereignty: the greatest lords of his own realm, who he believed were threatening what should have been his own supreme power in his kingdom. His great lords, on the other hand, thought they were exercising their customary right and duty to advise their king on the welfare and security of the realm. And it was a symptom of how wide the breach between them became, and how rapidly, that in 1386 – during a financial crisis in parliament – Richard declared that, if his subjects continued to rebel against him, he would seek the advice and help of his kinsman the king of France against them. This, it turned out, was not the most tactful thing to say when the cause of the financial crisis was the fact that a French fleet was massing in the Channel in preparation for a planned invasion.

Repeated crises between the king and his nobles came to a head in 1399 – by which time the 28-year truce with France had been sealed, and Richard was married to a nine-year-old French princess. In that year Richard tried to disinherit his cousin Henry Bolingbroke, duke of Lancaster, without any legal justification. The country would no longer support him in this tyranny, and Bolingbroke deposed the king and took his place as King Henry IV. But usurpation brings its own problems, and during a torrid 14-year reign – facing rebellion, financial crisis and chronic illness – Henry made no move to reactivate the English claim to France.

That was to change in 1413, with the accession of his son, Henry V. By this stage in his life, we should not be thinking of Henry as one of the lads. Whatever mischief Prince Hal had got up to, Henry V as King was a ruthless and formidably able ruler with an unyielding sense of his God-given purpose. We might want to relate this sense of mission to his earliest military experience: during his first command at the battle of Shrewsbury in 1403, at the age of just sixteen, Henry took arrow full in the face. Although the shaft was pulled out, the arrowhead was deeply embedded, six inches in, to one side of his nose. The wound had to be kept open for six weeks while the surgeon who was treating him designed and made a special implement to remove it. Somehow, without anaesthetic or antibiotic, Henry survived – although we might remember that the most famous portrait of him, which has come down to us in this later copy, shows him in profile, perhaps to disguise the scar he must have carried for the rest of his life. And along with the scar, he also carried a sense of his own invincibility, the certainty that God had not only saved but chosen him for a special destiny.

That destiny was to renew the claim to France bequeathed to him by his royal ancestor Edward III. And so, after two years of putting his house in order at home – a forensic and extraordinarily impressive process of restoring order to the country and to the royal finances – Henry launched his great expedition in August 1415. He had an army of something like 12,000 soldiers and perhaps twice that number of horses, as well as support staff and supplies, in a fleet of 1500 ships.

Henry knew his history, and although he was emulating Edward III in his claim to France, his tactics were different. During the fourteenth century, English armies had combined the 'chevauchée' – devastating raids across huge swathes of French territory – with the taking of particular fortresses, to be garrisoned and held as 'islands' of strategic power. But Henry wanted to take territory: to make good his claim by a systematic, relentless and disciplined advance into Normandy, across land that could then be ruled and crucially taxed to support further advances deeper into the heart of France itself. And he would start with port of Harfleur, a bridgehead that would hold the key to the invasion of Normandy in a way that the existing English possession of Calais, much further north, never could.

Henry succeeded in capturing Harfleur; but it took much longer and cost him far more than he had anticipated. Dysentery took hold among his men during the long weeks of the siege – and by the time the port fell, in late September, the force of fighting men still left to him was down to under 10,000, out of which he had to leave 1,200 to garrison and protect Harfleur, whose defences had been severely compromised by the English attack. He did not want to scurry back home straight across the Channel – that would hardly be the glorious statement of his rights and intentions that he had planned – but he could not afford to do much more before winter set in. He needed to regroup, and then return for a campaign of siege conquest proper.

So the plan he settled on was this: a march to Calais, to demonstrate his freedom of movement and his power in this kingdom he claimed as his, with the additional benefit of drawing the French military response away from Harfleur, whose walls had in places been reduced to rubble by English guns, and therefore might not be easily held by its new English garrison against a concerted French attack.

But on this march, Henry and his much reduced army encountered an obstacle, in the form of the river Somme. The threat of massing French forces meant that he was not able to cross the river where he had hoped, at Blanchetaque; and that in turn committed him to what turned into a total of eighteen days of forced march before his tired and hungry men – an army of somewhere under 8000 soldiers, with archers, longbowmen, outnumbering the men-at-arms by five to one – finally encountered the enemy at Azincourt.

So far, this is a narrative that is not so unfamiliar, or inconsistent with the unfolding of Shakespearean drama. However, we need now to consider not just the size of the French army that confronted Henry's Englishmen – but the political context that produced it.

The French had been through their own years of turmoil in the decades since the English and French had last met on a battlefield. Their king, Charles VI, the Well-beloved, had acquired a new epithet: by now he was also known as Charles the Mad. Back in 1392, at the age of just twenty-three, he had suffered a sudden fit of psychotic violence, attacking and killing five of his attendants before he could be overpowered and disarmed. This turned out to be the beginning of a chronic mental illness, with episodes of psychosis in which he believed that his wife and children were strangers, that he was not called Charles, that he was not king, even that he was made of glass and might shatter into a thousand pieces.

The king's incapacity was so devastating that it precipitated France into a period of intense political crisis. His closest relatives, the great lords of France, began to compete among themselves for control of his government and the profits that came with it – a competition that, as the years went on, simply could not be resolved. Every time the king came back to his senses, one set of decisions would be made. As soon as he lost them again, the decisions would be undone and countermanded. And all the time, tensions and rivalries among the most powerful men in the kingdom grew worse, until in 1407 the king's brother Louis, duke of Orléans, was attacked, hacked down and killed in a Paris street by servants of the king's cousin John the Fearless, duke of Burgundy.

This shocking murder meant that France was divided now not just by political rivalries but by a blood feud – and soon by civil war. Extraordinarily, John of Burgundy did not even attempt to deny the killing. Instead, he argued it had been justified because Orléans had been a tyrant and a traitor. That argument, of course, got nowhere with the duke of Orléans' young son or his allies, and by 1411 armies were in the field to fight the cause of the two factions now known as 'Burgundian' – after their leader the duke of Burgundy – and 'Armagnac', after the new duke of Orléans' father-in-law, the count of Armagnac.

Campaign followed truce and truce followed campaign – and the turns of fortune's wheel were now so violent that one observer in Paris – whose name is lost to history, but who kept a journal throughout these years – concluded wearily that 'the great all hated each other'. Both sides even looked for support to England in the last years of the troubled reign of Henry IV. Prince Hal, the future Henry V, was prepared to do business and send troops to help the Burgundians, in the periods when he exercised a dominating role in his father's government, while his father did the same with the Armagnacs.

So when Hal found himself on the throne and set about launching his invasion in 1415, he knew exactly what he was getting into and what moment he was taking advantage of. This was not simply a question of plucky England taking on the great might of France. Instead, it was the English, under the leadership of possibly the most able man ever to wear the English crown, ruthlessly seizing a moment at which it seemed that France was dismembering itself before enemy feet ever landed on French soil.

Of course, once it became clear that Henry's intentions were serious, and especially once it was apparent that Harfleur might fall, the great lords – however much they might hate each other – stirred in France's defence. A call to arms was sounded across northern France, and the poor mad king, with his teenage son, the dauphin, by his side, was moved to Rouen, the capital of Normandy, from where the defence of the kingdom would be organised.

Almost all the greatest lords of France who were capable of fighting answered this call – with the significant exception of the two greatest enemies within France's warring royal family, John of Burgundy and Charles, the young duke of Orléans. They, it seems, were given orders to stay away – a wise move on the part of the royal council to keep them apart and away from the fighting, given the danger that their own private war might spill over into the kingdom's campaign against the English. But in the end – since neither the king nor the dauphin would ride with their troops, because they were too vulnerable and too precious to risk on the battlefield – the decision was taken that the duke of Orléans should, after all, be there, as their nearest male relative. And even though the duke of Burgundy would not be present, his two brothers, the duke of Brabant and the count of Nevers, would join the royal army to represent him.

It was an imposing army, then; probably 12,000 troops or more. (The numbers on each side are still the subject of fierce academic argument; but what is clear is that the French had a much larger army, composed mainly of men-at-arms. The number of men-at-arms in the smaller English army was many times fewer, because the bulk of the English forces were made up of archers, of whom the French in turn had very few.) The French plan was to use their superior numbers to crush the English with an irresistible charge of heavy cavalry that would take out the archers, leaving the way clear for the greater force of French men-at-arms to overwhelm their English opponents.

On the morning of 25 October 1415, then, the two sides drew themselves up on open ground between the villages of Azincourt and Tramecourt and the woodlands that surrounded them. The English soldiers were exhausted after their long march, and suffering from the physically and psychologically debilitating effects of days of heavy rain. We have to remember, though, that conditions were much the same for the French troops, for whom the weather had been no kinder, and who had either been shadowing the English as they tried to find a crossing of Somme, or travelling at speed to join this hastily-arranged rendezvous.

It was clear that French had force of numbers on their side. What was less clear was that they had very little in the way of a plan. Or rather, they did have a plan, which was that their cavalry should charge down the English archers, their men-at-arms should advance, and that victory would follow. But this was a plan that had been devised well in advance of their arrival at the battlefield, and it therefore took no account of the ground over which the fighting would actually take place, or the possibility that tactics might need to change in response to the disposition of the enemy's forces.

Most important of all, therefore, was the fact that the French had no effective leadership, and no chain of command. Such planning as there had been had been undertaken by what was in effect a committee of lords, all conscious of their status and vying for honour rather than focusing on the specific threat that this bedraggled enemy might still represent. That was no replacement for what the English had: the vision of an experienced military leader with a cool head and implacable resolve, as well as the ability to communicate that resolve to his men.

The absence of an effective chain of command within the French forces was physically embodied within their front line, where all the great lords were jostling for a position of honour even if that meant leaving their men leaderless way behind them. And once the fighting started, this imbalance – not of numbers, but of leadership – immediately began to tell.

The first wave of the French cavalry charge, intended to overrun the archers placed on the two flanks of the English army ahead, found that they were riding into a storm of English arrows. The best longbow men – and English and Welsh archers were the best – could shoot almost continuously, and at close range the piercing heads of their arrows had a devastating effect even on men wearing plate armour, not to mention the animals they rode. Those who got through this dense rain of death found that they were riding on to death of a different kind: Henry had ordered each archer to plant a six-foot sharpened stake into the ground next to him, on which frightened horses suddenly found themselves impaled.

The cavalry charge on each flank, and the advancing men-at-arms who found themselves funnelled into an increasingly constricted space in between, continued to press forward as those at the front either fell or tried to turn back. And that produced devastation of a third and horrifying kind: the piling up of bodies of horses and men in the sucking mud, so that death might come by suffocation or crushing if not by arrow or stake. And once piles of helpless men and animals began to grow, the archers who carried short knives and axes at their belt could set about any still breathing with hacking blades.

There certainly was French hubris here: a certainty of their own glorious supremacy, and a fatal failure to take their enemy sufficiently seriously. But what we have to recognise is that this wasn't a reflection of Shakespeare's indolent and arrogant aristocrats; it was the outcome of a context in which France had had no effective leadership for years, resulting in a vicious and brutal struggle for power that undermined any attempt at concerted or focused resistance to one of the greatest war-leaders of the entire middle ages.

That is the context we need to understand if we are to understand not just the battle itself, but what came next. Agincourt did not lead straight on – Shakespeare-style – to Henry being recognised as the heir to the French throne and the establishment of 'English France'.

The battle did have powerful consequences. First of all, in practical terms, the French dead included many great nobles, including the dukes of Alençon and Bar, the Constable Charles d'Albret (the highest military officer in the kingdom), and the duke of Burgundy's two brothers. On top of that, still more princes of the blood were now prisoners: not only the duke of Bourbon and the count of Richemont, but most importantly Charles of Orléans, here shown in the Tower of London writing the poetry for which he would later become famous. The shape of the war with England and the war within France would be profoundly shaped by these French losses of personnel for the next two decades.

But not only that. Defeat at what the French called the 'wretched day' of Azincourt had profound effects too in political, conceptual and theological terms, which we underestimate at our peril.

The war of 1415 – like all medieval wars – was a conflict in which God had been involved from the very beginning. The outcome of battles, contemporaries believed, was always the result of God's will – and so, from the English point of view, interpreting what had happened that day was a matter of the utmost simplicity. Henry's claim to the throne of France – and also his dynasty's right to wear the crown of England – had been gloriously vindicated by his astonishing victory. The very fact that this was another David vanquishing an arrogant Goliath proved, to English eyes, that it was heaven's mandate in action. Henry was fighting a just war – and that was made absolutely plain in the account of the campaign written by one of the royal chaplains who had formed the spiritual corps of the English army, sitting behind English lines as the battle raged, praying furiously for divine intervention. Henry, this priest wrote, was the 'true elect of God', 'His own soldier'. Another chronicler reported in all seriousness that St George himself had been spotted on the battlefield, fighting on the English side.

The question, for Henry's uncle, the bishop of Winchester, addressing parliament in 1416, was this. Given that the English had won so many notable victories – he mentioned Sluys in 1340, Poitiers in 1356, and now Agincourt in 1415 – why were the French so slow to get the message? 'O God,' he said, 'why does this wretched and stiff-necked nation not obey these divine sentences, so many and so terrible, to which, by a vengeance most clearly made manifest, obedience is demanded of them?'

But for the French, explaining their defeat was much more difficult. It could not possibly be that the English were actually right. Instead, God must be using the English to punish the French, temporarily, for their sins. But, if sin was the heart of the matter, then whose sin was most at fault? And that question was unanswerable in the context of the brutal divisions within France, as each side pointed an accusing finger at the other. The net effect, therefore, of their defeat on the 'field of blood' at Azincourt was to redouble the violence of the civil war.

Henry, meanwhile, was a long way from achieving his objectives. He had his bridgehead at Harfleur, and God on his side – but it was the intensifying conflict between Burgundians and Armagnacs that gave him time to plan a new campaign, and then in 1417, when his new fleet was ready to sail, the perfect opportunity to advance across Normandy while France's domestic enemies fought for control of their own capital. And our Parisian observer was already coming round to the view that this English assault was no longer the worst of the horrors France had to face. 'Some people', he wrote, 'who had come to Paris from Normandy, having escaped from the English by paying ransom or some other way, had then been captured by the Burgundians and then a mile or so further on had been captured yet again by the Armagnacs, and had been as brutally and as cruelly treated by them as if by Saracens. These men, all honest merchants, reputable men, who had been in the hands of all three and had bought their freedom, solemnly affirmed on oath that the English had been kinder to them than the Burgundians had, and the Burgundians a hundred times kinder than the Armagnacs…'

With characteristically inexorable purpose, Henry was moving step by step across Normandy – taking first the castle and town of Caen, and with it Bayeux, then Alençon, Argentan and Falaise. Then, in January 1419, after a five-month siege, he finally starved Rouen, the great capital of Normandy, into submission. Two weeks after that, his forces were only thirty miles from Paris, and again our anonymous observer had some pithy points to make: 'No one did anything about it, because all the French lords were angry with each other, because the dauphin was at odds with his father on account of the duke of Burgundy, who was with the king, and all the other princes of the blood royal had been taken prisoner by the English king at the battle of Azincourt…'

But the key to Henry's triumph was not that battle; and it was not even his formidable advance into the heart of northern France during 1418 and the early months of 1419. The key to Henry's success in getting his hands on the crown of France – or at least much more nearly than any of his predecessors or his successors – was an event that took place on 10 September 1419.

The desperate search for a settlement between the Burgundians and the Armagnacs had produced frantic diplomacy in the summer months, with envoys meeting in all possible combinations: English and Burgundian, Burgundian and Armagnac, Armagnac and English. But the one that really mattered was the meeting convened in September between the duke of Burgundy himself and the Armagnac dauphin. (This was not the same dauphin who had been absent from the field at Agincourt – Charles VI's sons had a habit of dying young – but his youngest son, the new dauphin Charles.)

They met at Montereau, where the river Yonne gave into the Seine – and like many diplomatic meetings, this one was arranged for security reasons in the middle of a bridge. Both sides agreed to meet with no more than ten men each – and the meeting-place meant that neither could be ambushed by some hidden army. That afternoon, the dauphin and the duke gathered as arranged. Within the specially constructed wooden enclosure in the middle of the bridge, the duke knelt at the dauphin's feet. And then the man standing next to the dauphin – a former servant of the duke of Orléans named Tanguy du Châtel – buried an axe deep in the duke's skull.

It was a murder more precisely planned and more ruthlessly executed than the murder of the duke of Orléans himself in the streets of Paris twelve years earlier. It irretrievably altered the essence of the conflict, because now there could be no hope – no hope whatsoever – that reconciliation could be brokered between Armagnac and Burgundian.

And the direct result of that was a treaty, sealed at Troyes in May 1420, by which Henry V's ambitions finally came to fruition. There, in the cathedral, Henry bound himself to marry the French princess Catherine, daughter of the mad king Charles VI. In return, the mad king himself – speaking of course through the person of his loyal subject the new duke of Burgundy, son of the duke whose skull had been staved in at Montereau – disinherited the dauphin who had been responsible for that terrible crime, and recognised instead that Henry V should be the heir to France after the king's death, and regent of the kingdom until that time.

That is the true story that the gorgeous drama of Henry V leaves out: the creation of English France not through his victory at Agincourt – astonishing though it was – but through the bloody civil war in France, in which the dreadful defeat of Azincourt played a significant part. And by 1420 that conflict was so bitter, the hatred between the two sides so intense, that large parts of the kingdom – including the capital Paris – preferred to see the English king on the French throne than the 'so-called Dauphin'.

That was a story that would play itself out over the next thirty years: the battle for survival between English France in the north and the 'kingdom of Bourges' (as Armagnac France came to be called) in the south. And it was not a story with an inevitable ending. So we need to remember, in telling the story of Agincourt, that France could have ended up taking on a very different shape, geographically or politically; though what did eventually transpire takes us back to our 'greatest hits', and the extraordinary intervention of another charismatic military leader, every bit as certain as Henry V himself that God was on her side – the victories of the woman we know as Joan of Arc.

One final thought: England had its own civil war later in the fifteenth century – a conflict we call the Wars of the Roses. It began in earnest once all of Henry V's conquests in France were finally lost in 1450. And it came about because the son born to Henry and the French princess Catherine did not take after his father. Instead, he grew to be a king who was vague and indecisive, and increasingly mentally absent. No decision he made could not be overturned by the next person to whisper in his ear. In other words, he did not take after his father, but his maternal grandfather, the mad king Charles VI of France.

So if we want to understand the whole sweep of the fifteenth-century history of England and France – the huge and dramatic story that goes far beyond the glittering jewel of Shakespeare's Henry V – there are many reasons not to begin and end our tale with the battle of Agincourt.

© De Helen Castor, 2015