A map of the French-German front movement during World War I in the highlands of northern France. The dashed red line shows the furthest advance of the German Army. The red line with crosses is the Hindenburg line, a system of defenses built by the Germans. The solid thick red line is the battle line on Oct. 20th, 1918. This map is color-coded to show elevations from sea level to 2400 feet, and shows major cities, railroads, rivers, and landforms.