Thousands of men who were too old for military service had been employed there in building concrete fortifications, bombproof shelters and underground passages leading from one trench to another until the whole forest was a perfect labyrinth from which the Germans would have to be driven foot by foot and trench by trench. There were “pill boxes” by the hundred set up in concealed locations that commanded the entire territory. Snipers were in the lofty trees and machine gun nests existed by thousands. There were deep pits into which the unwary might fall. Barbed wire entanglements added to the natural difficulties of the position. Deep gulches and ravines made it impossible for the troops to advance in any kind of regular formations, and in places there was only room for them to go in single file over ground swept by enemy bullets. Their heaviest batteries had been brought from other portions of the line and concentrated there. It was the Germans’ last stand. If they failed to hold the Americans, their cause was lost. Back of the forest was the railway line that ran from Longuyon to Mezieres and Sedan. It was their chief artery of supplies for all their armies in France and Belgium. If the Americans once got astride of that railway, the Germans would be bottled up with no way of escape except through the gateway of Liege. Orders had gone out from the German High Command that the forest must be held at any cost, and their crack divisions of the Jagers and the Prussian Guards had been brought up with orders to die at their posts rather than retreat or surrender. They had all the advantage of position. They boasted that the forest could never be taken. Even the Americans whom the Huns had first learned to respect and afterward to fear, could not, it was said, do what was beyond the power of mortal men. It was simply impossible. Had not the great Napoleon himself declined to attack the enemy who held the forest in his day, saying that it was impregnable? But the American troops had learned to laugh at the word “impossible.” They wouldn’t admit that it was in their dictionary. They had been told that their green troops could not hold the Germans at the Marne, but they had held them. They had been told that it was impossible to break the Hindenburg line, but they had smashed it to bits. They had been told that the St. Mihiel salient could not be pinched out, but they did in two days what others had failed to do in four years. Now, when they heard that it was impossible to clear the Argonne Forest, they simply grinned. It was only a German joke. “Wonder when the music will begin,” said Frank, as he crouched beside Tom and Billy, waiting for the thunder of the great guns to signal the beginning of the attack. “It won’t be long now,” replied Tom, as he cast his eyes up to the sky where a faint light was beginning to diffuse itself. “I wonder if Stone is with this bunch of tanks in front of us,” remarked Billy.