For, granting that the Isthmus is in the Caribbean the predominant interest, commercial, and therefore concerning the whole world, but also military, and so far possessing peculiar concern for those nations whose territories lie on both oceans, which it now severs and will one day unite--of which nations the United States is the most prominent--granting this, and it follows that entrance to the Caribbean, and transit across the Caribbean to the Isthmus, are two prime essentials to the enjoyment of the advantages of the latter. Therefore, in case of war, control of these two things becomes a military object not second to the Isthmus itself, access to which depends upon them; and in their bearing upon these two things the various positions that are passed under consideration must be viewed--individually first, and afterwards collectively. The first process of individual consideration the writer has asked the reader to take on faith; neither time nor space permits its elaboration here; but the reasons for choosing those that have been named have been given as briefly as possible. Let us now look at the map, and regard as a collective whole the picture there graphically presented. Putting to one side, for the moment at least, the Isthmian points, as indicating the end rather than the precedent means, we see at the present time that the positions at the extremes of the field under examination are held by Powers of the first rank,--Martinique and Santa Lucia by France and Great Britain, Pensacola and the Mississippi by the United States. Further, there are held by these same states of the first order two advanced positions, widely separated from the first bases of their power; namely, Key West, which is 460 miles from Pensacola, and Jamaica, which is 930 miles from Santa Lucia. From the Isthmus, Key West is distant 1200 miles; Jamaica, 500 miles. Between and separating these two groups, of primary bases and advanced posts, extends the chain of positions from Yucatan to St. Thomas. As far as is possible to position, apart from mobile force, these represent control over the northern entrances--the most important entrances--into the Caribbean Sea. No one of this chain belongs to any of the Powers commonly reckoned as being of the first order of strength. The entrances on the north of the sea, as far as, but not including, the Anegada Passage, are called the most important, because they are so few in number,--a circumstance which always increases value; because they are so much nearer to the Isthmus; and, very especially to the United States, because they are the ones by which, and by which alone,--except at the cost of a wide circuit,--she communicates with the Isthmus, and, generally, with all the region lying within the borders of the Caribbean.