But the American charge had not been made in sufficient force. True, the Germans were driven from their improvised trenches, but the Yankee forces at the extreme front were numerically too small to pursue their advantage. They waited quietly for the arrival of reinforcements. Straight into the erstwhile trenches the tank driven by Hal now nosed its way. Its appearance was received with cheers by the men. Then it waddled crazily forward in pursuit of the foe. Hal was not given to unnecessary recklessness, and the fact that he advanced now while the bulk of the American troops remained beyond was not due to any spirit of foolishness. In passing, Hal was not aware of the fact that the most advanced troops were awaiting reinforcements. He thought that they would continue the pursuit at once. Therefore, in spite of the cries to stop that were raised behind, the tank ambled on. Then, so suddenly that it seemed that a curtain of blackness had been thrown about them, a fog descended over the field. In the advance of the tank, the German artillery and machine guns had been busy. A mine or two had exploded near the machine. Hal had been struck in the left hand by a tiny bit of shrapnel that found its way through one of the loopholes, but so slightly that the skin had only been bruised. Hal put the snout of the tank over the edge of a hill in the fog, but stopped in time to keep from end-over-ending down. Then he felt his way carefully down hill by a roundabout road. In the valley beyond there were machine gun nests and one seventy-seven field piece and some wandering trenches. In the hillside overhead were scores of burrow-like dugouts in which Germans had fortified themselves. In this direction Hal still guided his tank, confident that the American forces also were advancing under cover of the fog. Among the thousand shattering noises of battle, the approach of the tank had not been noticed. Suddenly the fog lifted, and for the first time Hal was conscious of the fact that his baby tank was unsupported by other tanks, or infantry, although the big American guns still sounded from behind. Nevertheless, Hal knew that the American advance was likely to be resumed at any minute. In spite of the lifting of the fog, the approach of the tank was still unperceived by the enemy. It is a constant source of wonder to tank crews that this happens so often. Locked up in their steel chamber and with a hammering gun they feel their roaring progress must herald them afar. Yet it often happens that they creep upon the enemy as though their beast had been shod with velvet. Hal saw the flare of the "77" and headed toward it. Bowers turned a stream of fire on it and the gun went out of action. The tank lurched on toward a long windrow of rusted wire. The wire shone red in the sun that had come out to dispel the fog. In successive alterations of the defense, it had been made into a pile fifty feet long, by twenty broad, and four feet high.