Ars-Sur-Moselle, a town in Alsace-Lorraine, administrative division of Lorraine, formerly belonging to the French department of Moselle, 5 m. S. W. of Metz, at the junction of the Mance with the Moselle; pop. in 1871, 5,330. In and near the town are important iron mines, iron forges, and paper mills. During the investment of Metz by the Germans in 1870, Ars had great strategical importance, as the railway from Nancy to Metz here crosses the Moselle; it was therefore selected as one of the principal depots of provisions for the army of Prince Frederick Charles.