of April, on the subject of changes that may have become necessary in forts and others means of defense, referred to this office for report, and to submit the following remarks in reply to the call, with regret that incessant occupations have not allowed me to bestow that care upon the report which the importance of the subject demands, and that the state of feeling in Congress and elsewhere seems to exact an early response to the resolution, however imperfect and immature that response is, in consequence:

In order to arrive at definite satisfactory conclusions as to whether any, and if so, what changes are necessary in the materials and construction of our forts and border defenses "in view of the important changes which have been made in ordnance and projectiles and in the methods of naval warfare," it must first be clearly seen and understood what purposes these defensive works are required and designed to serve.

As a general rule, with hardly an exception, the permanent defensive works of the United States were designed to forbid the passage through the waters subject to their fire of hostile vessels, or to prevent the use of such waters by an enemy in his vessels, or to secure the use of the waters for our own vessels.

So long as these forts fulfill these conditions our fortified ports, navy-yards, and harbors of refuge will be secure against injury from an enemy's ships, and the waters protected by them will be available for the use of our vessels and forbidden to those of an enemy; that is to say, these forts are designed as defenses against hostile military power afloat. They are not designed or expected to prevent the landing, at points beyond the reach of their fire, below them, or outside of them, of any hostile military array, or the movement of a force so landed from the place of its debarkation to any point beyond their scope. Provision against a land attack of the fortifications guarding the water is therefore made only to the extent of resisting assaulting columns that, landed from the ships and transports of the enemy, should attempt to take the batteries in rear. This provision is, of course, of greater magnitude, as the works are the more liable, from their great importance or their distance from succor, to such combined attacks.

A descent upon our coast and a march to the interior have always been intended to be met by other means of resistance. The land army of an enemy, transported to our shores and established upon them, it has ever been designed should be encountered and repelled by a like army of movable forces, mustered from the people and interposed between their homes and the invading force. But no such body of men, however numerous, however thoroughly appointed, armed, and disciplined, would be of any avail against even one small vessel-of-war armed with a few cannot of the most moderate caliber.

It is to afford competent resistance against this particular attack that sea-coast permanent batteries are provided. These batteries must have such armaments furnished them that an attempt by the vessels to attack them, or to evade them, will result in failure. But if, lon the contrary, the vessels shall land siege trains and sufficient force of men, then the forts must be succored by a superior force of men or they will be overcome in due time.

The following principles have always been maintained by engineers, viz:

Forts must fall before a competent land attack.

3 R R-SERIES III, VOL II