In the basin of the great American river Mississippi one may go forth on a spring morning with the sun brightly shining and a blue sky overhead, yet within a single hour all may be terribly changed. The wind suddenly begins to roar, and in a few minutes a storm bursts in awful fury. Whole forests are laid low; houses, villages, and towns are swept into ruin; men, women, and children lie dead beneath the stone and timber that sheltered them; the pride and labour of years are destroyed in a moment, and terror and desolation stalk the land. The terrible blast sweeps on, but gradually abates its ruthless might, and by nightfall all is calm again. The stars gleam brightly from the storm-swept sky, and the moon shines with a message of cheer to the survivors, who with the morning light begin to repair the ravages which they have suffered, and to go about their business once more, inspired by that hope which "springs eternal in the human breast." [Illustration: The Tornado of Fire which beat down upon the Russian Trenches on May 1, 1915. (_By permission of The Illustrated London News._)] Somewhat thus may we picture the Eastern arena of battle during the year 1915. A mighty tornado suddenly burst upon the Russian armies, and the whole aspect of the war was changed. The smiling sky of early April was a fierce rack of roaring thunder clouds by the middle of May. The onward sweep of the whirlwind could not be resisted; the Russians reeled beneath the shock; hundreds of thousands of their soldiers were swept into eternity, and for months hopeless ruin stared the survivors in the face. They recoiled before the terrible blast, and fell back into the vastnesses of their land, leaving behind them all the gains of nine months' hard battling. Whole provinces were yielded; great cities fell into the hands of their foes, yet with sublime resolution they still plodded eastwards until the fury of the storm began to abate. By this time they had knitted up their strength anew, and were strong enough not merely to resist the failing onset, but to make headway against it. And so it came about that the dire gloom of early summer brightened into new hope by autumn, and Russia's foes, though they had reft from her enormous tracts of territory, knew in their hearts that they had failed. They had aimed at utterly destroying their enemy, but they had done nothing of the kind, and the new territory which they had won was likely to become a Pandora's[53] chest of troubles. By the end of the year they were strung out on a line of nine hundred miles, across the marshes and plains of Russia. * * * * *