The Mad War (la Guerre folle in French), also known as the War of the Public Weal, is a late Medieval conflict between a coalition of feudal lords and the French monarchy.

It occurs during the regency of Anne of Beaujeu in the period after the death of Louis XI and before the majority of Charles VIII.

The war begins in 1485 and ends in 1488.The principal lords involved are Louis II of Orléans, the cousin of the king (and future Louis XII of France); Francis II of Brittany; René II, Duke of Lorraine; Alain d'Albret; Jean de Châlon, Prince of Orange; and Charles, Count of Angoulême.

Other leading lords support the revolt, including Philippe de Commines and Odet d’Aydie, count of Commines and governor of Guyenne.As a revolt against French royal authority it is supported by the foreign enemies of the King of France: England, Spain and Austria.

Its principal outcome is the absorption of Brittany into the French kingdom.