FORT AMORY.

The Trent River is a very weak feature in the defenses of New Berne, compelling two distinct lines dependent for communication upon a bridge, liable to be burned at any moment, and giving the enemy the opportunity of concentrating upon either line. Last summer the river was guarded by one or two gun-boats which afforded a measure of protection to the small works, Amory and Gaston, exposed to assault from their advanced positions. These works are located upon the high ground where the bank is bluff, permitting a flotilla of small boats or a column of infantry to pass with comparative security in dark and stormy weather. Upon an examination with General Palmer and Colonel Dutton, something was deemed essential for the Trent side. This conviction was greatly strengthened by the information that the officers do not like to have their gun-boats in the Trent. The absence of the naval element and the expectation of an early attack, decided that a slight extension of Amory was imperatively demanded. Colonel Dutton, one of the most accomplished engineers in the service and of great experience, has looked after this work. It will command the Trent, and have a cross-fire upon all the approaches to Fort Totten, besides making us independent of gun-boats in that quarter.

ORDNANCE.

The preceding observations upon the general system of defense apply with equal force to the armament of the fortifications. While no water attack was expected the old ordnance in North Carolina, when I assumed command, would have sufficed. Not so now. Two iron-clads menace us, and may at any moment attempt to recover the command of the sounds, in conjunction with land forces. In view of this sudden revolution in the rebel means of attack, what artillery has this army which can be depended upon to destroy these iron-clads in the absence of Federal iron-clads? It has only seven suitable rifles, six of which were here when no iron boats were dreamed of. A 200-pounder and 100-pounder are at Plymouth. A 100-pounder is at Hatteras, two are at Fort Macon, and two at New Berne.

In case the iron-clad passes Plymouth, Roanoke Island and Hatteras will be visited. One rifle is needed at Hatteras, to replace the one moved to Plymouth, and one at Macon, to replace the gun removed to New Berne. Guns are burst and otherwise crippled in active service, and there should be at this depot at least one or two extra for such contingencies. The Southfield burst a 100-pounder in extricating the Bombshell in the Chowan.

On the 24th, Commander Flusser was expecting the iron-clad and an attack at Plymouth, and wrote to Commander Davenport urgently for a 100-pounder rifle for the Southfield. Had I an extra gun I could served our naval friends at a time when it would have been appreciated.

If these considerations have any force at all, the number of (seven) guns asked for by the ordnance officer on the 14th instant is quite as small as is proper. What has been done are such modifications as seemed imperatively called for in view of the public interest intrusted to me. Had they not been made, and disaster befallen us, the Government, and the major-general commanding the department, would not have excused me for delaying to communicate with the engineer officer at Fort Monroe.

Conclusion. - The criticisms in the letter on "Fortifications and armaments" are based upon principles, and are unanswerable. The views set forth on the 29th March have been verified in the clearest manner by the fall of Plymouth. The defenses on the left of Fort Williams (the central work) consists of open works, and are dependent upon the gun-boats. The gun-boats were forced out of the river, the iron-clads attacked these works in rear, and they soon became untenable. The land forces entered the town on that flank. Had all the works been inclosed, the results would have been very different. When we were at Plymouth I called your attention to this feature of the system of defense.

I am, very respectfully, your obedient servant,

JOHN J. PECK,

Major-General.

Major General B. F. BUTLER,

Commanding Dept. of Va. and N. C., Fort Monroe, Va.