On Easter Monday, April 13, 1360, a catastrophic hailstorm struck the English army encamped near Chartres, France, killing an estimated 1,000 soldiers and thousands of horses during the Hundred Years' War. The storm was so severe that it was interpreted by contemporaries as divine intervention, a punishment for the English campaign. This event contributed to the negotiations that led to the Treaty of Brétigny, temporarily halting the conflict and reshaping the political geography of France.

The Black Monday hailstorm became a powerful symbol of divine judgment in contemporary chronicles and later English poetry, serving as a reminder of the fragility of human ambition against the forces of nature. The event was recorded by chroniclers such as Jean Froissart, whose vivid descriptions of the storm influenced later poetic treatments of war and providence. The storm's literary legacy can be seen in the tradition of English battle poetry that uses weather as a metaphor for moral and political disorder, a theme that would reach its zenith in works like Shakespeare's King Lear.