Black Monday (1360)

Black Monday took place on Easter Monday (1360) during the Hundred Years' War (1337–60), when a huge hail storm struck and killed an estimated 1,000 English soldiers. The storm was so devastating that it caused more English military casualties than any of the previous battles of the war.

Siege of Chartres
On 5 April 1360, Edward III of England led his army of 10,000 men (including approximately 4,000 men-at-arms, 700 continental mercenaries, 5,000 mounted archers ) to the gates of Paris. Headed by the king's most trusted lieutenants; including the Prince of Wales, Henry, duke of Lancaster, the earls of Northampton and Warwick and Sir Walter Mauny: men who had been responsible for many of the English military successes in the preceding two decades, in one of the largest English armies fielded in the Hundred Years' War. The defenders of Paris led by the Dauphine of France (Charles V), refused battle. It was not possible to breach the defenses, so over the next week Edward would try to induce the Dauphine into battle. All attempts at the latter would prove futile and undermine Edward's hope for a decisive outcome. The English left the vicinity of Paris after laying waste to the countryside, and marched towards the French cathedral city of Chartres.

On Easter Monday April 13, Edward's army arrived at the gates of Chartres. The French defenders again refused battle, instead sheltering behind their fortifications, and a siege ensued. The French defense was low in numbers and led by the 35th Abbot of Cluny, Audrouin de La Roche.

That night, the English army made camp outside Chartres in an open plain. A sudden storm materialized and lightning struck, killing several people. The temperature fell dramatically and huge hailstones along with freezing rain, began pelting the soldiers, scattering the horses. Two of the English leaders were killed, and panic set in among the troops, who had little to no shelter from the storm. One described it as "a foul day, full of myst and hayle, so that men dyed on horseback [sic].” Tents were torn apart by the fierce wind and baggage trains were strewn around. In a half-hour, the incitement and intense cold killed nearly 1,000 Englishmen and up to 6,000 horses. Among dead and injured was the eldest son of Thomas de Beauchamp, the 11th Earl of Warwick. Sir Guy de Beauchamp died of his wounds sustained during the storm two weeks later on the 28th of April and was buried in Vendôme, France.

Edward was convinced the phenomenon was a sign from God against his endeavors. During the climax of the storm he is said to have dismounted from his horse and kneeled in the direction of the Chartres Cathedral. He recited a vow of peace and was convinced to negotiate peace with the French.

Shortly after the Abbot of Cluny arrived at the English camp with peace proposals. Edward agreed with the counsel of his trusted aid Henry of Grosmont, the 1st Duke of Lancaster. That day Edward began the withdrawal of his army from the gates Chartres, effectively ending the one-day siege of the town.

Aftermath
French friar Jean de Venette credited the apocalyptic storm as the result of the English looting of the French countryside during the observant week of Lent.

On May 8, 1360, three weeks later, the Treaty of Brétigny was signed, marking the end of the first phase of the Hundred Years' War.

The legacy was mentioned in Shakespeare an work:

"“It was not for nothing that my nose fell a- bleeding on Black Monday last, at six o'clock i' the morning.” —Shakespeare: Merchant of Venice, ii. 5."