It was supposed to be just another masquerade. As daylight turned to dusk on 28 January 1393, servants rushed through the halls of the Hôtel Saint-Pol in Paris, making the final arrangements for what promised to be an evening of fun and revelry. Large spreads of food were set out on tables; musicians readied their instruments. And, in an adjoining room, six young noblemen were being sewn into costumes of linen and flax, to resemble the wild wood savages of fairy tale legend. They were to be the centerpiece of tonight's entertainment; their identities hidden by masks, they were to prance and howl before the throngs of delighted guests, who would laughingly try to guess at who they were. As the six dancers talked and joked with one another, speaking softly as the first of the guests began to file into the ballroom, no one could have known that the night would only end in flames and death and would worsen the fragile mental state of the king.

The king, in fact, was one of those six young men, donning his flaxen costume. Charles VI of France had had a strenuous year – barely six months ago, he had been seized by a fit of psychosis in the forests of Le Mans, which led him to murder four of his own knights in a blind fury. After he had been subdued, he slipped into a coma which lasted four days, during which time whispers proliferated throughout the kingdom that he had been the victim of poison or witchcraft. When the king awoke, he recovered his mental faculties and immediately expressed grief over what he had done. He sought penance from God, attending mass and taking confession, before retiring to the countryside castle of Creil, where he hoped the fresh air might improve his health. In his absence, several powerful courtiers hovered over the throne like vultures, ready to snatch the dominant seat on the Regency Council should the king's condition worsen. Fortunately, Charles VI returned to Paris before the end of the year, ready to resume his rule. His physicians, however, were still worried about his health and recommended he not take on any tasks that might induce too much stress and bring on another mental break.

It was partially for the king's benefit that his wife, Queen Isabeau of Bavaria, decided to host a masked ball on the Tuesday before Candlemas. Officially, the party was a celebration of the third marriage of one of her ladies-in-waiting, Catherine de Fastaverin, to a groom of the king's court. The remarriage of a widow was traditionally an occasion for mockery and mischief, and, since Catherine had been twice widowed, this applied twofold for her. Queen Isabeau and her friends, therefore, decided to throw a charivari, the most outrageous of medieval parties, which were often characterized by fun disguises, debaucherous dancing, and loud, discordant music. The queen knew that the main event of the night had to be something particularly spectacular, and so she turned to someone who only knew how to think in spectacular terms. This was Huguet de Guisay, a young courtier who had developed a reputation as a prankster and deviser of mischievous schemes. A serial womanizer and professional partier, Huguet often took his revelries too far – he took sadistic pleasure in humiliating and beating common-born servants, whom he would call dogs and hit with the flat end of his sword. If a servant displeased him, Huguet would make him lie on the ground and kick him with spurs, snarling "Bark dog!" in response to the poor man's howls of pain.

It was this rather unsavory nobleman who suggested the main spectacle of the evening: the six dancers disguised as wild men, or wood savages. The choice of ‘wood savages' as the disguise was itself quite provocative, since in medieval Europe, wood savages were mythical figures who lived outside of the grace of God. They were usually depicted as filthy, shaggy brutes who lived in the dark woods away from civilization, lacking souls or human emotions. They danced by firelight, conjuring demons and other unholy spirits; it was this demon-summoning ritual that Huguet hoped to imitate tonight. He thought the use of paganistic wood savages would be a perfect way to tease the bride-to-be, since remarriage was considered sacrilegious. The fact that the dance would make some stuffy church officials squirm was, to Huguet, an added benefit. Queen Isabeau excitedly agreed to the idea and suggested that her husband be one of the dancers – he could certainly use the fun, and it might amuse the rest of the guests to learn that the king had been one of the wild men dancing before them.

So it was, on that fateful evening, that King Charles VI was being sewn into a costume of flax linen soaked with resin so that he appeared "shaggy and hairy from head to foot." The other five dancers were all young men and friends of the king's – Huguet de Guisay was one, as well as Sieur de Nantouillet, Comte de Joigny, Aimery de Poitiers, and Yvain de Foix, the bastard son of Comte de Foix. Their costumes were highly flammable, and so the torches were to be held on sconces on the ballroom wall, far from where the dancers would be. The queen and her friends went to great lengths to warn the guests against holding torches or bringing any open flames near the dancers. Once all was ready, the musicians began to blare their loud and noisy music, and the guests began to crowd the ballroom. The dancers shared one last mischievous glance with one another, donned their masks, then followed one another into the party.

The six wild men strode into the room, dancing in front of the guests and making bawdy gestures. Laughter filled the air, mixing with the strange, discordant music. Presently, one of the wild men came up to the 15-year-old Duchess of Berry, who, much to her surprise and delight, recognized him as the king. Except for her and the queen, no one else seemed to realize that the king was amongst the group of wild savages, who danced in a large circle, stopping every now and then to howl like wolves. It was around this time that two young nobles stumbled into the ballroom. One was Louis I, Duke of Orléans, the king's 20-year-old younger brother, and the other was his friend Philippe de Bar. The two youths had spent the last few hours drinking in another part of the palace. From the way they staggered in, it was clear that they had become quite drunk. Any guest not focusing on the spectacle of the six dancing wild men may have noticed the room grow a hint brighter when the two young men entered, for both were carrying torches.

Laughing, Louis of Orléans approached one of the dancers and held out his torch, hoping to get a glimpse at the man's face. In doing so, several sparks fell from the torch and landed on the man's costume – in an instant, the dancer burst into flames. His screams were barely heard over the din of the music, as the flames greedily ate at the resinous wax that covered his costume, devouring him whole. It did not take long for the flames to spread, engulfing another dancer, then another. When the guests realized what was happening, they began to scream and panic, elbowing one another to get away from the burning men writhing before them. Queen Isabeau, unaware which of the dancers was her husband, let loose a shrill cry before fainting. Luckily, the young Duchess of Berry had thought quickly and thrown her long skirts over the king, thus shielding him from the flames. The act likely saved his life. Another of the dancers, the Sieur de Nantouillet, caught fire, but leapt into a wine cooler that had been filled with water. He, too, was saved.

The other four men were not so lucky. They screamed and screamed as the flames melted their costumes onto their very skin. One chronicler gruesomely described how their flaming genitals dropped to the floor, releasing a stream of blood. Several guests ran forward to help the burning men, sustaining severe burns of their own as they tried to smother the flames. They eventually succeeded, but it was much too late. Comte de Joigny was already dead, burned to a smoldering crisp on the ballroom floor. Yvain de Foix and Aimery de Poitiers lingered for two days with agonizing burns before they both succumbed to their injuries. Huguet de Guisay, the instigator of the whole affair, was the last to die, living for three painful days before expiring. He spent his last hours cursing his fellow dancers, both the living and the dead. Despite the horrific nature of Huguet's death, the common people had not forgotten his cruelty; when his coffin was carried through the streets of Paris, they cheered and greeted it with mocking cries of "Bark, dog, bark!"

In the days that followed, news of the tragedy spread throughout France. It came at a time when the kingdom's stability was already balancing on a knife's edge – the last few years had seen corrupt regents, tax revolts, and the king's flirtation with madness while, across the Channel, England watched and waited for a chance to finish the bloody work of the ongoing Hundred Years' War. So when the French people learned of the tragedy – soon to be known far and wide as the Bal des Ardents, or 'Ball of the Burning Men' – they were justifiably angry, believing that their king's life had been thrown into jeopardy for no good reason. The whole affair just seemed to exemplify the needless decadence and extravagance of courtly life. To quell this dissent, the king solemnly rode to Notre Dame Cathedral with his uncles walking penitently behind him. Louis of Orléans, that reckless youth who was rightfully being blamed for the disaster, sought absolution by donating large sums of money to the construction of a Celestine monastery. But this money had previously been gifted to him by the king, leaving one historian to wonder whose soul, exactly, was being absolved.

Within the next few months, the grumbles of dissent began to die down, and the survivors moved on the best they could from the traumatic incident. The king, however, was never able to move on. Already mentally unwell, the near-death experience only accelerated the onset of his next bout with psychosis, which lasted on and off for seven months. He forgot who he was, unable to remember that he was the king or even that his name was Charles. He did not recognize his wife, Queen Isabeau, and ran in terror whenever she approached him, shouting, "Who is that woman, the sight of whom torments me?"

His mental breaks would become more frequent and more dangerous as, on one occasion, he believed that he was made of glass. The king's madness drove the kingdom into chaos and, ultimately, led to civil war as various factions struggled for control of the Regency Council. The Ball of the Burning Men, while a tragic incident in its own right, marked a defining moment for medieval France, paving the way for the instability that would lead to civil war – and, ultimately, to the invasion of King Henry V of England, who would take advantage of Charles' madness and change the course of the Hundred Years' War at a place called Agincourt.