Similarly, it will be observed that the strain of trade defence was proportioned not to the volume of that trade, but to the number and exposure of its terminals and focal points. Whatever the volume of the trade these remained the same in number, and the amount of force required for their defence varied only with the strength that could readily be brought to bear against them. It varied, that is, with the distribution of the enemy's bases and the amount of his naval force. Thus in the war of 1812 with the United States, the West Indian and North American areas were much more exposed than they had been when we were at war with France alone and when American ports were not open to her as bases. They became vulnerable not only to the United States fleet, but also in a much higher degree to that of France, and consequently the force we found necessary to devote to trade defence in the North Atlantic was out of all proportion to the naval strength of the new belligerent. Our protective force had to be increased enormously, while the volume of our trade remained precisely the same. This relation of trade defence to terminal and focal areas is of great importance, for it is in the increase of such areas in the Far East that lies the only radical change in the problem. The East Indian seas were always of course to some extent treated as a defended area, but the problem was simplified by the partial survival in those regions of the old method of defence. Till about the end of the seventeenth century long-range trade was expected to defend itself, at least outside the home area, and the retention of their armament by East Indiamen was the last survival of the practice. Beyond the important focal area of St. Helena they relied mainly on their own power of resistance or to such escort as could be provided by the relief ships of the East Indian station. As a rule, their escort proper went no farther outward-bound than St. Helena, whence it returned with the homeward-bound vessels that gathered there from India, China, and the South Sea whaling grounds. The idea of the system was to provide escort for that part of the great route which was exposed to attack from French or Spanish colonial bases on the African coasts and in the adjacent islands. For obvious reasons this system would have to be reconsidered in the future. The expansion of the great European Powers have changed the conditions for which it sufficed, and in a war with any one of them the system of defended terminal and focal areas would require a great extension eastward, absorbing an appreciable section of our force, and entailing a comparatively weak prolongation of our chain of concentrations. Here, then, we must mark a point where trade defence has increased in difficulty, and there is one other.