The Treaty of Monçon or Treaty of Monzón was signed on 5 March 1626 by Cardinal Richelieu, the chief minister of Louis XIII and Gaspar de Guzmán, Count-Duke of Olivares, the chief minister of Philip IV of Spain, at Monçon (modern Monzón) in Aragon. It was signed in the aftermath of the French capture of Valtellina from Papal troops, ending the Valtellina War and also concluded the First Genoese-Savoyard War.