Jemappes (zhəmäpˈ) [key], town, Hainaut prov., S Belgium. It is a coal-mining center of the Borinage region. Manufactures include iron and steel. At Jemappes in 1792 the French under Dumouriez defeated the Austrians under Duke Albert of Saxe-Teschen in one of the first important battles of the French Revolutionary Wars. The victory opened the way to Brussels for the French.