"Think, boys, of the size of a modern army. One single army corps of two divisions of three brigades each, contains over 43,000 combatants. Of this, over one half is infantry, the rest including the machine gun sections, the field artillery, the heavy artillery, the siege artillery and engineering and signal corps. It takes 9,000 non-combatants in the field to look after this army, the train including ten provision columns, with special field bakeries and field slaughter-houses, ten ammunition columns, twelve field hospitals, to say nothing of special bridge sections and a host of minor but essential units. Picture to yourselves the amount of food which has to be transported to feed these 52,000 men three times a day, most of which has to be brought from long distances to the front and there cooked and distributed. Conceive the thousands of tons of cartridges and shells needed to supply the infantry and the various kinds of artillery! "The Line of Communication is the only thing which keeps an army going, which enables it to operate. If that be cut, the guns are silenced and the army starves. It is absolutely imperative to every advancing army that its rear, its Line of Communication, be safe from attack by the enemy. It is the artery which carries its life-blood. You can easily see that, for such an immense transportation work, control of the railways of a country is the first chief need of an invading army. No wagon system could provision an army or keep it supplied with munitions. "Liége is Belgium's eastern railroad center. Six miles north of the forts of Liége lies the frontier of Holland. South of Liége lies the broken, mountainous country of the Ardennes, uncrossed by railways and impossible as a line of transport. Troops could only march through the difficult Ardennes country if they were sure of being able to secure supplies when they had reached the other side. "Certainly, Deschamps, as you suggest, the German Army could divide and march by roads north and south of Liége. Suppose it did so. What then? After the main army had passed, we could sally forth from Liége, cut the Line of Communication and, by starvation and lack of ammunition, compel the surrender of the whole invading army. "No, boys, not only must the Germans enter Liége, but they must capture every single fort before it is safe for them to proceed. Not until the last gun is silenced in Forts Loncin, Flemalle and Boncelles is Western Europe threatened. When Liége falls, Belgium falls, and if the fall comes too quickly, the whole of Western Europe may go." "But will Liége fall?" asked Horace. "That," answered the master, "is what we are going to see." He held up his hand for silence. "The shots are coming nearer," he said. The words were hardly out of his mouth when the ground shook with a heavy detonation and both the boys staggered. "That was not a German shell," declared the old reservist; "that was one of our forts replying."