Scores of thousands of men may be packed away waiting motionless for the word, more thousands may be pouring slowly up the communication ways, and still more thousands standing ready a mile or two behind the lines; and yet to any eye looking from the enemy's side the country is empty and still, and bare of life as a swept barn. Even the all-seeing airmen can be cheated, and see nothing but the usual quiet countryside, the tangled crisscross of trenches, looking from above like so many wriggling lines of thin white braid with a black cord-center, the neat dolls' toy-houses and streets of the villages, the straight, broad ribbon of the Route Nationale, all still and lifeless, except for an odd cart or two on the high road, a few dotted figures in the village streets. Below the flying-men the packed thousands are crouched still to earth. At the sound of the engine's drone, at sight of the wheeling shape, square miles of country stiffen to immobility, men scurry under cover of wall or bush, the long, moving lines in the trenches halt and sink down and hang their heads (next to movement the light dots of upturned, staring faces are the quickest and surest betrayal of the earth-men to the air-men), the open roads are emptied of men into the ditches and under the trees. For civilized man, in his latest art of war, has gone back to be taught one more simple lesson by the beasts of the field and birds of the air; the armed hosts are hushed and stilled by the passing air-machine, exactly as the finches and field-mice of hedgerow and ditch and field are frozen to stillness by the shadow of a hovering hawk, the beat of its passing wing. But this time some movement in the trenches, some delay in halting a regiment, some neglect to keep men under cover, some transport too suspiciously close-spaced on the roads, betrayed the movement. His suspicions aroused, the airman would have risked the anti-aircraft guns and dropped a few hundred feet and narrowly searched each hillside and wood for the telltale gray against the green. Then the wireless would commence to talk, or the 'plane swoop round and drive headlong for home to report. And then, picture the bustle at the different headquarters, the stir amongst the signalers, the frantic pipings of the telephone "buzzers," the sharp calls. "Take a message. Ready? Brigade H.Q. to O.C. Such-and-such Battery," or "to O.C. So-and-So Regiment"; imagine the furtive scurry in the trenches to man the parapets, and prepare bombs, and lay out more ammunition; the rush at the batteries, the quick consulting of squared maps, the bellowed string of orders in a jargon of angles of sight, correctors, ranges, figures and measures of degrees and yards, the first scramble about the guns dropping to the smooth work of ordered movement, the peering gun muzzles jerking and twitching to their ordained angles, the click and slam of the closing breech-blocks, the tense stillness as each gun reports "Ready!" and waits the word to fire.