At their feet the road dropped steeply into a little valley, filled with woods which ran right up the slope beyond and disappeared into a smoky mist on the opposite crest. The sun had not fulfilled its early promise, and had disappeared by noon. A small drizzling rain was beginning to fall. Helen Ryker, who loved her personal comforts, drew her blue cloak more closely round her, and shivered. “They don’t have any trenches _here_,” she announced, in aggrieved tones. “They are in the woods down in the valley,” Miss Lane assured her. “You can hear the firing.” You certainly could. Up to their ears from the undergrowth on every side rose the mutterings of warfare—solitary rifle-shots, and the intermittent pup-pupping of machine guns. Down in the valley, at the foot of the road, they could see a stream. The road had once crossed it by a bridge; but the bridge was now a ruin, and the road had been diverted so as to cross higher up, by some sort of pontoon. Not a human being was in sight. One of the strangest characteristics of modern warfare—warfare in which millions of men are employed where formerly hundreds sufficed—is the entire invisibility of the combatants. In these days of aeroplanes and magnifying periscopes no man ever makes himself more conspicuous than need be. A hundred years ago soldiers went into action in brightly coloured coats and flashing accoutrements. Now their uniforms imitate the colours of nature—the colours of grass and earth. Guns are painted to look like logs of wood. If a sniper wishes to do a little business from a tree-top or a thicket, he not infrequently paints himself green as a preliminary. “It’s lonesome here!” continued Miss Ryker. “I expect we shall find the boys presently,” replied the undefeated Frances. “My gracious, Helen, what was that?” Over their heads—quite close, it seemed—sailed something invisible, with a weary sigh. It was a howitzer shell fired from an American battery five miles behind them. The sound of its passage ceased, but almost directly afterward a column of greenish-grey smoke spouted up from the wooded hillside opposite, followed a few seconds later by a heavy detonation. Helen and Frances found themselves unaffectedly gripping hands. “What is it?” asked Helen tremulously. One of Miss Lane’s most compelling characteristics was that she was never at a loss for an answer. “That? That’s artillery fire, I guess. That over there is the smoke of a big gun.” As usual, she was partially correct. What they saw and heard was, indeed, artillery fire, but it was not the smoke of the gun, but the smoke of the shell bursting among the German machine-gun nests. “German or American?” asked Helen. “American, sure. Let’s go on down this road, and see some more. It’s a nice quiet road. There can’t be any danger.”