It is not the taking of individual ships or convoys, be they few or many, that strikes down the money power of a nation; it is the possession of that overbearing power on the sea which drives the enemy’s flag from it, or allows it to appear only as a fugitive; and which, by controlling the great common, closes the highways by which commerce moves to and from the enemy’s shores. This overbearing power can only be exercised by great navies, and by them (on the broad sea) less efficiently now than in the days when the neutral flag had not its present immunity.[32] It is not unlikely that, in the event of a war between maritime nations, an attempt may be made by the one having a great sea power and wishing to break down its enemy’s commerce, to interpret the phrase “effective blockade” in the manner that best suits its interests at the time; to assert that the speed and disposal of its ships make the blockade effective at much greater distances and with fewer ships than formerly. The determination of such a question will depend, not upon the weaker belligerent, but upon neutral powers; it will raise the issue between belligerent and neutral rights; and if the belligerent have a vastly overpowering navy he may carry his point, just as England, when possessing the mastery of the seas, long refused to admit the doctrine of the neutral flag covering the goods. 11. STRATEGIC FEATURES OF THE GULF OF MEXICO AND THE CARIBBEAN[33] In the special field proposed for our study, there are two principal points of such convergence—or divergence: the mouth of the Mississippi River, and the Central-American Isthmus. At the time when these lectures were first written the opinion of the world was hesitating between Panama and Nicaragua as the best site for a canal through the Isthmus. This question having now been settled definitively in favor of Panama, the particular point of convergence for trade routes passing through the Caribbean for the Pacific will continue at Colon, whither it for so long has been determined because there is the terminus of the Panama Railroad.