In the late 1300s, King Charles VI of France began to suffer from a bizarre mental illness now known as the “glass delusion.” He genuinely believed that he was made of fragile glass, and that any physical contact could cause him to shatter into pieces. This wasn’t just a passing fear it completely changed how he lived and ruled.

Charles VI became king at just 11 years old. At first, he was known as Charles the Beloved, but in his early twenties, he began to show signs of mental instability. In one famous incident, he randomly attacked his own knights, believing they were enemies, and killed several men before being restrained. After this, his behavior became more and more erratic , including long periods of forgetting who he was, refusing to bathe or change clothes, and believing he was made of glass.

Terrified that even sitting down or being touched might shatter his “glass” body, Charles wore reinforced clothing sometimes with iron rods sewn into them to “protect” himself. He wouldn’t let anyone touch him and often avoided sitting down or moving too quickly. Guards and servants were told to be extremely gentle around him, and some even carried cushions in case he fell. Court life had to be carefully adjusted to accommodate his bizarre and fragile belief.

Because of his delusions and repeated mental breakdowns, Charles was often unfit to rule, which threw France into political chaos. His relatives and nobles fought for power in his absence, which weakened the monarchy. His mental illness eventually led to civil war between two powerful factions (the Burgundians and the Armagnacs), and France became vulnerable contributing to the Hundred Years’ War dragging on much longer.

The “glass delusion” wasn’t unique to Charles several nobles and scholars in medieval Europe reported similar fears, often tied to feelings of extreme anxiety, pressure, and fragility. But Charles VI is the most famous and tragic example. His life reminds us how mental illness was misunderstood and often impossible to treat in earlier centuries, even for kings. Despite being one of the most powerful men in Europe, Charles lived much of his life terrified of breaking.