Day after day the American troops moved slowly forward, over rugged, difficult ground, broken by ravines and steep hills, through dense underbrush, in the face of deadly fire from artillery and nests of machine guns hidden in every vantage point, through incessant rain and mud and fog and penetrating cold, pushing the enemy steadily back, until they reached Sedan, cut the German Army’s most important line of communication, and so brought the end of the war in sight. For a few days later came the German request for an armistice and terms of peace. Aiding the fighting men at the front were non-combatant troops who by their courage and zeal helped greatly and won high honor. Regiments of engineers worked with the lines at the front, keeping the roads open, building railways, repairing bridges in front of the advancing lines to enable them to pour across in pursuit of the fleeing enemy, and, in the earlier months, mining and tunneling under the enemy’s lines and constructing trenches. Much of the time they worked under fire and it sometimes happened that, suddenly attacked, they seized rifles from the dead and wounded around them and fought back the assaulting party. The camoufleurs worked close behind and sometimes at the front, disguising roadways, ammunition dumps, artillery and machine gun positions, concealing the advance of troops, most of the time in the shelled areas and often under fire. Immediately behind the front lines during the St. Mihiel and Meuse-Argonne offensives and under the protection of camouflage the map makers and printers of the American Army had big rotary presses on trucks and turned out the necessary maps at once as they were needed. British and French lithographers had told them it could not be done, but their mobile map-making trains kept in touch with the army, turning out a million maps during the Argonne drive. The Signal Corps gave services of such inestimable value that without them the successes of the combatant troops would have been impossible. The war enlarged the personnel of the Corps from 1,500 to 205,000, of whom 33,500 were in France, where they strung 126,000 miles of wire lines alone, of which 39,000 miles were on the fighting fronts. Their duties were varied and highly specialized and demanded the greatest skill and efficiency. Regardless of danger the personnel of the Corps carried on their work with the front lines, went over the top with the infantry, and even established their outposts or radio stations in advance of the troops. A non-combatant body, it lost in killed, wounded and missing, 1,300, a higher percentage than any other arm of the service except the infantry. Its photographers made over seventy miles of war moving picture films and more than 24,000 still negatives, much of both within the fighting areas.