AISNE, an, a river in northern France, with a total length of 280 miles. A tributary of the Oise, the Aisne rises in the Argonne Forest, flows north and then west, joining the Oise above Compiegne (on the left bank), after passing Vouziers, Rethel and Soissons, tak ing in on the way its affluents the Aire and Vesle, on the latter of which stands Rheims.
It flows through the departments of Marne, Ardennes, Aisne and Oise. From Mouron for about 170 miles the river is used for floating lumber; from Chiteau-Porcien it is navigable for 75 miles, and from Neufchatel, about 15 miles below that point, there is considerable traffic. A lateral canal runs from Vouziers to Conde— above Soissons. The Canal des Ardennes (62 miles long) begins at Conde, below which the Aisne is canalized and con nected with the Meuse. The lateral canal of the Aisne is connected with that of the Marne at Conde-sur-Marne by a 36-mile canal. On its north side the Aisne has a line of steep ridges, the scarp of a great plateau, at an average of a mile or more from the stream. The height of the scarp varies from some 200 feet, where the uplands begin on the west above Compiegne from the Forest of the Eagle, to more than 450 feet 30 miles east in the high bluffs of Craonne. Beyond this latter place the Aisne takes a wide sweep to the northeast toward its source, and the banks fall to the lower level characteristic of the shallow dales of Champagne. From Compiegne to Craonne the section is everywhere of the same type, with occasional deeper ravines. For the most part the lower• slopes are steep and clothed with grass. The plateau stretches back for some miles, till at La Fere and Laon it breaks down into the plains of northeastern France. It was the crest of this plateau that
the German armies had chosen at an average of two miles from the river bank— on which to make a stand after they had been hurled back on the Marne (q.v.) in September 1914. The position was well chosen, for it was one of enormous strength, extending from a point on the heights of the Meuse north of Verdun westward across the Argonne and the plain of Champagne to Rheims, where it turned north west along the Forts de la Pompelle, Nogent l'Abesse, Berru and Brimont, and across the Aisne near its confluence with the Suippe to Craonne, whence it ran westward along the heights of the Aisne to the Forest of the Eagle, north of Compiegne. During their advance to the Marne the Germans had Ieft parties of sappers behind to entrench the Aisne position —in case of necessity. How that necessity actually arose from the historic battle of the Marne is told elsewhere (See WAR, EUROPEAN). That battle began 6 Sept. 1914; on 8 September General von Kluck's army was in full retreat and on the 9th von Buelow's army followed. On the 10th the battle was over and the British and French became the pursuers. On the 12th the Ger mans were in position on the Aisne, and on the 13th the Allies began the passage of the river. The first phase of the battle of the Aisne closed on 18 Sept. 1914, and from that day began the remarkable trench warfare that became so prominent a feature of the great war.