of fuel and supplies, from a place near the distant point; and equally, if we are to receive an attack upon the coast, it is well to have a base far out, in order to embarrass the transit of the enemy toward our coast, by the threat—­first against his flank, and later against his rear and his communications.  Naval bases looked at from this point of view resemble those forts that European nations place along their frontiers.

It is true that any base placed at a salient has the weakness of all salients, in that fire can be concentrated on it from several directions; and a naval base has the added disadvantage of a more difficult withdrawal, if attacked by an overwhelming force, and a longer line of communications that has to be protected.  But this weakness all distant bases have, from the fact that they are distant; and, naturally, the more distant they are, the more difficult it is to support them, because the longer are their lines of communications.

Distant naval bases, therefore, are vulnerable in a high degree; they are vulnerable both to direct attack and to an attack on their lines of communications; and the factors that help a base in one way injure it in another.  If a naval base is placed on a rock, or a rugged little island that holds nothing else, and on which a hostile army could not land, it is very safe from land attack; whereas, if it is placed on a large and fertile island, on which an invading army could easily land, it is extremely vulnerable to land attack.  But, on the other hand, the naval base on the inaccessible island could be starved out by simply breaking its lines of communications, while the naval base on the large and fertile island might be able to survive indefinitely, even though the communications were wholly ruptured.

The establishment of any permanent distant naval base is a matter of great expense, even if the natural conditions are favorable.  But favorable conditions have rarely existed; and the expense of establishing such bases as Malta, Gibraltar, and Heligoland has been tremendous.  An important consideration has been the fact that, unless the base were made so strong that it could not be taken, it might be better not to attempt to fortify it, on the theory that it would be better to let a poor naval base fall into the hands of the enemy than a good one.  To this reasoning, the answer is usually made that no base can be made absolutely impregnable, and that sufficient defense will be provided if it makes the task and cost of capturing the base greater than the base is worth.  This means simply that the more valuable the base is, the more money should be spent in defending it; and that it is worse than useless to defend it by any means that is obviously too small, in proportion to its value.