If a base at Guantanamo would not meet our necessities in case of an invasion of the Caribbean by a naval fleet superior to ours, then it seems idle to discuss the value of Guantanamo relative to some other place, no matter how good the position of Guantanamo may be, and no matter how nearly it may approximate to adequacy.
There is no real usefulness in having a naval base anywhere, unless that naval base can accomplish the purpose for which it is desired.
A naval base is desired for purposes of war, and for no other purpose whatever; and to decide on a position for a base without keeping this fact clearly in view, is to act on an underestimate of the situation, the folly of which has been pointed out in previous pages.
We may conclude, then, that in deciding on the place for a distant permanent naval base, on which the operations of a whole fleet are to base for war, we should select the best site available, even if military strength and resources may have to be added to it artificially--unless in the case of any site considered the difficulties of adding them are insuperable.
The last sentence may seem like shirking the whole question, because it does not state what "insuperable" means; so it may be well to add that in modern days few engineering difficulties are insuperable, as the existence of the fortress at Heligoland shows.

If the submarine and the mine did not exist, the difficulties would be greater than they actually are; because guns alone, no matter how carefully mounted and protected, could hardly be expected to keep off indefinitely the attack of a heavy fleet, or even to save from injury the fighting and auxiliary vessels anchored in its waters.

But the submarine and mine combine to keep fighting ships at distances greater than those over which ship's guns can fire, and reduce the amount of fortification required on shore.
One of the principal sources of expense in establishing bases at some points would be that of dredging out harbors sufficiently extensive, while harbors sufficiently extensive are provided already by nature in such localities as Samana.

But, as pointed out before, harbors on large islands can be taken from the land side, as was Port Arthur; and adequate protection from land attack is, in many cases, almost impossible if the enemy has command of the sea, as a superior hostile fleet would have in the Caribbean; while the hills and waters of Culebra and Vieques Sound could long defy not only actual invasion, but any fleet attack.
This brings us face to face with the fact that it may be less expensive to establish and protect a naval base situated on a little island, even if an artificial harbor has to be constructed, than to establish and protect a base on a large island, even if the base on the large island has a large natural harbor and can be more easily defended against bombardment from the sea.

It would be cheaper, for instance, to protect a base on Culebra than one at Guantanamo, or even Samana, if the enemy commanded the sea; and cheaper to protect a base on the forbidding rocks of Polillo or Guam than on the large and fertile island of Luzon, with its extensive gulfs and bays, in many of which a fleet in command of the sea could land its force; because protecting a base on a large island would require covering a very large area, and perhaps a long extent of coast.
Aircraft may exercise an important influence on the choice of the position of a base, perhaps in the direction of choosing a base on a large island rather than on a small one; since the great speed of aircraft tends to lessen the importance of having the base out a great distance from home--so far as purposes of scouting are concerned.
It seems probable also that aircraft will soon be recognized as inherently adapted to preventing the landing of hostile troops, by dropping bombs on the troops, while they are in process of disembarkation, while proceeding in small boats to the shore, and while in the act of landing on the beach, with their guns, ammunition, supplies, horses, and impedimenta of various kinds.
_Co-operating Bases_ .-- Discussion of the relative values of positions for bases, say in the Caribbean, should not blind our eyes to the fact, however, that no nation is prevented from establishing as many bases as it needs, wherever its flag may float; that the United States, for instance, is not debarred from establishing permanent naval bases at both Guantanamo and Culebra, should such a procedure seem desirable.