as the necessity of fitness, a body where long service and small reserves obtain should in peace be more numerous than one where the reserves are larger.  To long service and small reserves a large standing force is the natural corollary.  It may be added that it is more consonant to the necessities of warfare, and more consistent with the idea of the word “reserve,” as elsewhere used in war.  The reserve in battle is that portion of the force which is withheld from engagement, awaiting the unforeseen developments of the fight; but no general would think of carrying on a pitched battle with the smaller part of his force, keeping the larger part in reserve.  Rapid concentration of effort, anticipating that of the enemy, is the ideal of tactics and of strategy,—­of the battle-field and of the campaign.  It is that, likewise, of the science of mobilization, in its modern development.  The reserve is but the margin of safety, to compensate for defects in conception or execution, to which all enterprises are liable; and it may be added that it is as applicable to the material force—­the ships, guns, etc.—­as it is to the men.

The United States, like Great Britain, depends wholly upon voluntary enlistments; and both nations, with unconscious logic, have laid great stress upon continuous service, and comparatively little upon reserves.  When seamen have served the period which entitles them to the rewards of continuous service, without further enlistment, they are, though still in the prime of life, approaching the period when fitness, in the private seaman or soldier, depends upon ingrained habit—­perfect practical familiarity with the life which has been their one calling—­rather than upon that elastic vigor which is the privilege of youth.  Should they elect to continue in the service, there still remain some years in which they are an invaluable leaven, by character and tradition.  If they depart, they are for a few years a reserve for war—­if they choose to come forward; but it is manifest that such a reserve can be but small, when compared with a system which in three or five years passes men through the active force into the reserve.  The latter, however, is far less valuable, man for man.  Of course, a reserve which has not even three years’ service is less valuable still.

The United States is to all intents an insular power, like Great Britain.  We have but two land frontiers, Canada and Mexico.  The latter is hopelessly inferior to us in all the elements of military strength.  As regards Canada, Great Britain maintains a standing army; but, like our own, its numbers indicate clearly that aggression will never be her policy, except in those distant regions whither the great armies of the world cannot act against her, unless they first wrench from her the control of the sea.  No modern state has long maintained a supremacy by land and by sea,—­one or the other has been held from time to time by this or that country, but not both.  Great Britain wisely has chosen naval power; and, independent of her reluctance to break with the United States for other reasons, she certainly would regret to devote to the invasion of a nation of seventy millions the small disposable force which she maintains in excess of the constant requirements of her colonial interests.  We are, it may be repeated, an insular power, dependent therefore upon a navy.