Third. There is both a theoretical and a practical limit, already reached, to the thickness of the armor that can be used upon vessels of war. There is doubtless also a limit to the weight of the guns that those vessels can carry. Already guns have been manufactured and tested capable of throwing projectiles three or four times heavier than has been found sufficient to destroy the thickest armor afloat.

166. Errors in the enemy's defense.

Fort Wagner affords a striking example of the injudicious location of an outwork. Its office was to hold and control possession of all that portion of Morris Island upon which effective breaching batteries against Fort Sumter could be established.

We have seen how signally it failed to do so. The instructive and suggestive lesson of Fort Pulaski, which fell because Big Tybee Island, the proper position for a heavily armed outwork, was abandoned to us without an attempt being made to hold it, was lost upon the enemy.

167. The great mistake of the enemy, therefore, on that part of his line of defenses which we attacked, was made by his engineer, and consisted in locating Fort Wagner near the north end of Morris Island instead of on the sand-hills, 2 miles farther south, near Light-House Inlet. He would not have been forced to witness the humiliating spectacle of the destruction of his principal work on an interior line over the heads of the defenders of an exterior one, had Fort Wagner been even 1 mile farther to the southward. With only one inclosed work for the defense of the island, the proper location for it was near the south end. Its armament should have been defensive principally, and its strength of profile such as to enable it to resist a coup de main beyond peradventure. The heavy ordnance for channel defense on the north end of the island ought ot have been in single or two-gun batteries, as they were on the south end. Too much dependence, however, was placed on these guns. Their resistance to our attack on the 10th of July was by no means formidable. A few light field pieces, judiciously posted and secured against capture by assault, would have been far more efficient.

168. A proper and perfect defense of Morris Island would have been two small inclosed works, each heavily stockaded to resist escalate, and each armed with a few field and siege pieces and several siege mortars. With one such work located on the site of Fort Wagner, and another on the high sand bluffs about 2 miles farther south, no enemy could have maintained a lodgment on the island for an hour. The long-range guns for channel defense should have been placed in one or two gun batteries, located so as to be seen in flank or reverse by the inclosed works.

169. On the hypothesis that the enemy did not deem it necessary to hold all of Morris Island, and considered Fort Sumter safe so long as he kept us away from Fort Wagner, the latter work was as judicious in its location as it was formidable in its construction. But in that view of the case, which our subsequent operations proved to be short-sighted and faulty, the batteries of heavy guns for channel defense ought to have been kept within reach of Wagner's protecting fire, and not placed over 2 miles distant, as were many of those we captured on the 10th of July. A wise defense would have kept us off Morris Island entirely, as the simplest and least expensive method of solving the problem.