The German Empire was an industrial state, and its needs were imperious. In the face of a rapidly increasing population the nation became more and more dependent upon importations of foreign foodstuffs. Herculean efforts were made to keep agricultural production abreast of the domestic demand for grain: transient laborers were imported from Russia and Italy to replace those German peasants who had migrated to the industrial cities; machinery was introduced and scientific methods were applied; high protective tariffs were imposed upon imported foodstuffs to stimulate production within the empire. These measures, however, were insufficient to meet the situation; the greatest intensive development of the agricultural resources of the nation could not forestall the necessity of feeding some ten millions of Germans on foreign grain.[31] German manufacturers, as well, were unable to obtain from domestic sources the necessary raw materials for their industrial plants. Many essential commodities were not produced at all in Germany and in only insignificant quantities in the colonies. Some German industries were almost wholly dependent upon foreign sources of supply for their raw materials. The most striking example of this was the textile manufactures, which had to obtain from abroad more than nine tenths of their raw cotton, jute, silk, and similar essential supplies.[32] Interruption of the flow of these or other indispensable goods would have brought upon German industrial centers the same paralysis which afflicted the British cotton manufactures during the American Civil War. The German Empire had to pay for its imported foodstuffs and raw materials with the products of its mines and factories, with the services of its citizens and its ships, with the use of its surplus funds, or capital.[33] The development of a German export trade was the natural outcome of the development of German industry. And as German industries expanded, the demand for imported raw materials increased, thus rendering more necessary the extension of the export trade. The German industrial revolution of the late nineteenth century was at once the cause and the effect of the growing dependence of German economic prosperity upon foreign markets.[34]