And, taking their turns at being "observation sentinels," Jimmy and his chums strained their eyes as they looked across dark and rainy No Man's Land for the first sign of any activity on the part of the Germans. There was a tense feeling in the air, as though something portended, and this feeling had a basis in fact, for shortly before dawn the German batteries suddenly opened fire on the line of trenches held by Jimmy, his chums, and others of the 509th. "Are we going over the top?" cried Bob, as, by the distant flashes of fire from the German guns, he saw their platoon officer. It was safe to talk, or even shout, now, for there was no danger of giving an alarm to the Huns. "Are we going over the top?" "Not in the face of that fire, at all events," was the grim answer. "The Boches have started the ball in earnest." Every second the blasts from the German guns increased in intensity, and their effect was felt in the trench that sheltered the Khaki Boys. "What's the matter with our artillery?" cried Jimmy. "Why don't they give Fritz some of his own medicine?" And, as if in answer, a moment later came a thunderous response from the American lines. "There they go!" cried Roger. "Now things will even up." It was an awful artillery duel, and there were heavy casualties on both sides. While the artillery was firing from either side of No Man's Land there was little the Sammies could do save to shelter themselves as best they could behind the parados. These were sand bags, built up at intervals behind the parapet. They afforded as good protection against high explosive shell fire and shrapnel as could be obtained in trench warfare. And as they were practically impenetrable by machine gun bullets, if a soldier could get behind the heavy bags he was comparatively safe. But many of them were burst apart or blown away by the missiles from the German guns, and it became necessary, if the boys in the trench were to have protection, to replace the bags. Accordingly orders were given to do this, and details were told off, some to fill bags and others to put them in place. Roger and Bob were engaged in this last when Bob suddenly gave a cry and caught his left hand in his right. "Hit?" cried Roger, for there was light enough, caused by the flashes from many guns, for him to see Bob start. "Just a scratch," was the answer. It was more than a scratch--being a rather deep flesh wound across the back of Bob's hand. But with the aid of Roger he quickly bound it up in a bandage, after applying an antiseptic, and then kept on with the vital work of making the trench safer. Many were wounded and many killed on both sides by that night firing, and after an hour of bombardment on both sides there had come no order for the Sammies to go over the top. "Don't we get the word?" asked Jimmy of Bob, as they had a moment's respite from building up the parados.