Argonne (ärgônˈ) [key], region of the Paris basin, NE France, in Champagne and Lorraine (Meuse, Marne, and Ardennes dept.), a hilly and woody district centering around the capital, Sainte-Menehould. Thinly populated, with unimportant cultivation and only small industries, it has been of strategic significance. There, in 1792, the French repulsed the Prussians. The sector was a battleground throughout World War I. In the Allied victory drive (Sept.–Nov., 1918), the Meuse-Argonne sector was carried by the Americans.