Answer
The Bal des Ardents was a lavish masquerade ball held in Paris in 1393 to celebrate the marriage of King Charles VI of France to Isabeau of Bavaria. During the festivities, a fire broke out, most likely due to a torch igniting the costumes of the dancers. The flames spread rapidly, engulfing the room and causing the deaths of several guests, including the Duke of Orléans, the King's brother.