The _relative_ importance of cities and towns is less varied by the fluctuations of commerce on a land frontier than on the sea-coast. The ever-changing system of "internal improvements," by furnishing new highways and thoroughfares for the transportation of the products of manufacturers and agriculture, either continually varies the relative standing of the seaports already opened, or opens new ones for the exportation of these products, and the importation of foreign articles received in exchange. But these "internal improvements" are seldom carried so far as to connect together two separate and distinct countries, and consequently the principal places on the dividing line usually retain their relative importance, no matter how often they may have declined during times of hostility, or again flourished with the increased commercial intercourse which results from peace. The principal European places of traffic near the frontiers have remained the same for ages, and in all probability ages hence the great frontier marts will be nearly the same as at present. This stability of rank among border towns is not confined to commercial influence; the same holds true with respect to that established by intercourse of a hostile character. Military history teaches us that lines of hostile operations, and the fields upon which the principal battles between any two countries have been fought, are nearly the same, no matter how remote the periods of comparison. These points and lines, so important in commerce as well as in war, result from the natural features of the ground, and we ought therefore to expect that they would be as little liable to sudden changes as the character of the earth itself. From these remarks it will readily be perceived that there are three distinct methods of determining the strategic points between this country and Canada: 1st, by an examination of the topography of the two countries; 2d, by tracing out the main channels of commercial intercourse; 3d, by reviewing the lines of their military operations. The last method is the least liable to error, and perhaps is the most easily understood, inasmuch as it is sometimes difficult to point out the precise degree of connection between prospective military lines and the channels of commerce, or to show why these two have a fixed relation to the physical features of the country. In the present instance, moreover, this method furnishes ample data for the formation of our decision, inasmuch as the campaigns between this country and Canada have been neither few in number nor unimportant in their character and results.