Its principal function in war would be to shorten the long trip that our vessels would have to make without refreshment, and therefore the length of their lines of communications, and to enable our vessels to arrive in enemy's waters in better condition of readiness for battle than would otherwise be the case.
We have thus far considered the best position for an advanced naval base, in the case of operations against one country only.
It seems clear that, if we are to consider operations against two countries separately, and at different times, we should be led to conclude that the case of each country should be decided individually; in the case of wars with Norway and Portugal, for instance, the best places for our two bases would be as close to the home bases of those countries as possible; and even in the case of fighting two simultaneously, the conclusion would be the same, if the two countries were in widely different directions from us--as are Switzerland and China.

If we consider the case of war against two contiguous countries simultaneously, however, it would seem better to have one base, situated similarly toward the home bases of the two countries as toward two different home bases in one country--since the two countries would be, in effect, allies; and their fleets would act in reality like separated portions of one fleet.
As the United States possesses no island on the Atlantic side which is nearer to foreign countries than to our own, and as our interests for the immediate future lie mostly on the Atlantic side, it may be well now to apply the general principles just considered to the question of where is a naval base most urgently needed under actual conditions.
Imagining a war between us and some one European naval Power, and imagining a war also between us and two or three allied European naval Powers, and realizing the length of our Atlantic and Gulf coasts, extending from Maine to Panama, a glance at the map shows us that, apart from the home naval bases on our continental coasts, the position on American soil which is the closest to European bases is on the little island of Culebra, which occupies a salient in the northeastern end of the Caribbean Sea.[*] [Footnote *: The acquisition by the United States of the island of Saint Thomas, about 20 miles east of Culebra, if accomplished, will extend the salient just so much farther toward Europe.] The only reason an enemy would have for entering the Caribbean would be an intention to attack the Panama Canal region, or an intention to establish an advanced base, from which he could conduct more or less deliberate siege of our Atlantic coast and cities.

In either case, our fleet would be seriously handicapped if it had no adequate base in the Caribbean; because its line of communications north would be exposed to the enemy's operations at all times; and seriously wounded American ships would have little chance of getting repairs; little chance even of making successfully the long trip to Norfolk or New York.
In case the enemy fleet should start from Europe fully prepared in every way, we should be in ignorance of its intended destination; and as the enemy fleet would be stronger than ours (otherwise it would not start) it would doubtless be able to destroy our undefended station at Guantanamo, seize some suitable place in the West Indies, say the Bay of Samana, and then establish a base there, unless we had first seized and fortified all suitable localities; and the United States would then find itself in the anomalous position of being confronted near its own coasts with an enemy fleet well based for war, while her own fleet would not be based at all.

Not only would the enemy fleet be superior in power, but it would possess the strategical advantage, though far from its own shores.

The situation, therefore, about a month after the foreign fleet left Europe, would be that the Caribbean Sea would contain a hostile fleet which was not only superior to ours in power, but was securely resting on a base; while ours had no base south of Norfolk, the other side of Hatteras.