Permanent fortifications differ in many of their features from either of the two preceding elements of national defence. They are passive in their nature, yet possess all the conservative properties of an army or navy, and through these two contribute largely to the active operations of a campaign. When once constructed they require but very little expenditure for their support. In time of peace they withdraw no valuable citizens from the useful occupations of life. Of themselves they can never exert an influence corrupting to public morals, or dangerous to public liberty; but as the means of preserving peace, and as obstacles to an invader, their influence and power are immense. While contributing to the economical support of a peace establishment, by furnishing drill-grounds, parades, quarters, &c.; and to its efficiency still more, by affording facilities both to the regulars and militia for that species of artillery practice so necessary in the defence of water frontiers; they also serve as safe depots of arms and the immense quantity of materials and military munitions so indispensable in modern warfare. These munitions usually require much time, skill, and expense in their construction, and it is of vast importance that they should be preserved with the utmost care. Maritime arsenals and depots of naval and military stores on the sea-coast are more particularly exposed to capture and destruction. Here an enemy can approach by stealth, striking some sudden and fatal blow before any effectual resistance can be organized. But in addition to the security afforded by harbor fortifications to public property of the highest military value, they also serve to protect the merchant shipping, and the vast amount of private wealth which a commercial people always collect at these points. They furnish safe retreats, and the means of repair for public vessels injured in battle, or by storms, and to merchantmen a refuge from the dangers of sea, or the threats of hostile fleets. Moreover, they greatly facilitate our naval attacks upon the enemy's shipping; and if he attempt a descent, their well-directed fire will repel his squadrons from our harbors, and force his troops to land at some distant and unfavorable position. The three means of permanent defence which have been mentioned, are, of course, intended to accomplish the same general object; but each has its distinct and proper sphere of action, and neither can be regarded as antagonistical to the others. Any undue increase of one, at the expense of the other two, must necessarily be followed by a corresponding diminution of national strength. We must not infer, however, that all must be maintained upon the same footing. The position of the country and the character of the people must determine this.