The Nancy affair (French: Affaire de Nancy) - commonly referred to in English as the Nancy Mutiny - was the crushing of a military mutiny in France on 31 August 1790, two years before the final overthrow of the French Monarchy. The mutiny was of particular significance in that it illustrated the degree to which the discipline and reliability of the Royal Army had been undermined by thirteen months of revolutionary turmoil.
The Nancy Mutiny occurred at a time when unrest was spreading amongst the regular regiments of the French Army, following the fall of the Bastille, the mutiny of the gardes-francaises (French Guards) and the forced relocation of the royal family from Versailles to Paris in 1789. While the officers of the army were still predominantly royalist, the rank and file were becoming increasingly influenced by the revolutionary turmoil around them. During the first half of 1790 a number of acts of disobedience and small scale mutinies occurred in various units and political associations were created with links to Jacobin and other parties outside the army. Specific military grievances were widespread amongst the soldiers, relating mainly to harsh discipline and conditions of service. Particularly resented was a measure taken in 1781 to reserve officer commissions to members of the nobility. This restriction had alienated many non-commissioned officers who now had no chance of promotion beyond their existing rank.
In August 1790 the garrison of Nancy in northeastern France comprised three regiments of the old Royal Army. These were the Régiment du Roi (King's Regiment), the Régiment de Châteauvieux (one of the twelve regiments of Swiss mercenaries in the French infantry) and the Mestre-de-camp cavalry. The soldiers' committee of the Regiment du Roi demanded to audit the regimental accounts, arrested the quartermaster, confined the colonel and other officers to barracks and seized the unit's pay chest. The Chateauvieux followed suit - a particularly disturbing development from the perspective of the royal court since the Swiss regiments were assumed to be the most reliable element within the army. The officers of the Chateauvieux were able to temporarily restore order and punish members of the soldiers' committee according to the Swiss military code - in this case by running the gauntlet. This action led to renewed disturbances, now involving all three regiments of the garrison.