Though McCormick had invented his reaper in 1831, and though many rival machines had appeared in the twenty years preceding the Civil War, only the farmers on the great western plains had used the new machinery to any considerable extent. The agricultural papers and agricultural fairs had not succeeded in popularizing these great laborsaving devices. Labor was so abundant and so cheap that the farmer had no need of them. But the Civil War took one man in three for the armies, and it was under this pressure that the farmers really discovered the value of machinery. A small boy or girl could mount a McCormick reaper and cut a dozen acres of grain in a day. This circumstance made it possible to place millions of soldiers in the field and to feed the armies from farms on which mature men did very little work. But the reaper promoted the Northern cause in other ways. Its use extended so in the early years of the war that the products of the farms increased on an enormous scale, and the surplus, exported to Europe, furnished the liquid capital that made possible the financing of the war. Europe gazed in astonishment at a new spectacle in history; that of a nation fighting the greatest war which had been known up to that time, employing the greater part of her young and vigorous men in the armies, and yet growing infinitely richer in the process. The Civil War produced many new implements of warfare, such as the machine gun and the revolving turret for battleships, but, so far as determining the result was concerned, perhaps the most important was the reaper.