Again, the most perturbing feature of the relations between the European powers also contributed to produce an eagerness for colonial possessions. Europe had entered upon the era of huge national armies; the example of Prussia, and the rancours which had been created by her policy, had set all the nations arming themselves. They had learned to measure their strength by their available man-power, and in two ways the desire to increase the reserve of military manhood formed a motive for colonisation. In the first place, the surplus manhood of a nation was lost to it if it was allowed to pass under an alien flag by emigration. Those continental states from which emigration took place on a large scale began to aspire after the possession of colonies of their own, where their emigrants could still be kept under control, and remain subject to the obligations of service. Germany, the state which beyond all others measures its strength by its fighting man-power, was most affected by this motive, which formed the chief theme of the colonial school among her politicians and journalists, and continued to be so even when the stream of her emigrants had dwindled to very small proportions. In a less degree, Italy was influenced by the same motive. In the second place, conquered subjects even of backward races might be made useful for the purposes of war. This motive appealed most strongly to France. Her home population was stationary. She lived in constant dread of a new onslaught from her formidable neighbour; and she watched with alarm the rapid increase of that neighbour's population, and the incessant increases in the numbers of his armies. At a later date Germany also began to be attracted by the possibility of drilling and arming, among the negroes of Central Africa, or the Turks of Asia Minor, forces which might aid her to dominate the world.