Aisne ayn, River, is a river in northeastern France. It rises in the forests of Argonne near Ste. Menehould. It flows north and then west before joining the Oise River near Compiegne. The Aisne is about 180 miles (290 kilometers) long. Canals join the Aisne to the Seine and Meuse rivers. Three bitter battles of World War I (1914-1918) were fought in the valley of the Aisne.