The gray mist that was fog-gas hung over everything. There was a definite breeze blowing, but the mist was so dense that it did not seem to move. It was far enough from the fog-flares for the last least trace of striation to have vanished. Fifteen miles to the north the fog-flares were placed, ranged by hundreds and by thousands, burning one after another as the fog service set them off, and sending out their incredible masses of thick gray vapor in long threads that spread out before the wind, coalesced, and made a smoke-screen to which the puny efforts of the last war--the war that was to make the world safe for democracy--were as nothing. Here, fifteen miles down wind from the flares, it was possible to see clearly in a circle approximately five feet in diameter. At the edge of that circle outlines began to blur. At ten feet all shapes were the faintest of bulks, the dimmest of outlines. At fifteen feet all was invisible, hidden behind a screen of mist. "Cast around," said Coffee gloomily. "Maybe we'll find a shell, or tracks of a tank or somethin' that chucked the gas here." * * * * * It was rather ludicrous to go searching for anything in that mass of vapor. At three yards distance they could make each other out as dim outlines, no more. But it did not even occur to them to deplore the mist. The war which had already been christened, by the politicians at home, the last war, was always fought in a mist. Infantry could not stand against tanks, tanks could not live under aircraft-directed artillery fire--not when forty guns fired salvos for the aircraft to spot--and neither artillery nor aircraft could take any advantage of a victory which either, under special conditions, might win. The general staffs of both the United States and the prominent nation--let us say the Yellow Empire--at war with it had come to a single conclusion. Tanks or infantry were needed for the use of victories. Infantry could be destroyed by tanks. But tanks could be hidden from aerial spotters by smoke-screens. The result was fog-gas, which was being used by both sides in the most modern fashion when, their own unit wiped out and themselves wandering aimlessly in the general direction of the American rear, Sergeant Coffee and Corporal Wallis stumbled upon an American pill-box with its small garrison lying dead. For forty miles in one direction and perhaps thirty in the other, the vapor lay upon the earth. It was being blown by the wind, of course, but it was sufficiently heavier than air to cling to the ground level, and the industries of two nations were straining every nerve to supply the demands of their respective armies for its material.