CHARLESTON, May 20, 1862.

Brigadier-General EVANS, Adams Run:

The enemy's gunboats within the Stono: keep your advanced pickets within sight of them. Move negroes back.

J. C. PEMBERTON,

Major-General, Commanding.

HDQRS. DEPT. OF SOUTH CAROLINA AND GEORGIA, Charleston, S. C., May 21, 1862.

Colonel A. L. LONG,
Military Secretary, Headquarters Commanding General:

COLONEL: I have the honor to acknowledge the receipt of an official letter of the 19th instant from the commanding general. In reply to his inquiry as to my information of the strength of the enemy I regret to say that I have none which I consider reliable. General Evans estimates about 10,000 in front of his line, basing his opinion on the number of camps, &c. General Hunter has his headquarters on Daufuskie Island. I have no means of approximating the number of his troops on that Island, Hilton Head, Saint Helena, or Port Royal. Most of his forces have been withdrawn from the neighborhood of Port Royal Ferry, though small incursions for negro stealing are represented to have been recently made from that direction. I do not think he has to exceed a regiment at Pulaski and the immediate neighborhood.

As the result of the inexcusable and gross neglect of duty on the part of those having charge of the steamer Planter, recently abducted by her negro crew, the enemy yesterday [doubtless availing of the knowledge of said crew] entered the Stone River with two gunboats and anchored off Battery Island, shelling on either side as they passed. All our guns and public stores of every description had been withdrawn and the buildings were fired as the infantry withdrew. I do not suppose there is any immediate intention of a tacking Charleston; this movement, however, may be a commencement with that object in view. Our land defenses on James Island, however, are very strong. The battery constructed at Elliott's Cut, on the Stono River [not yet entirely completed], mounts only eight guns. I desire to make it twenty, but under present arrangements cannot effect it. I do not regard Charleston as strong. What under the old system of warfare was our strength is now our great weakness. The many approaches by water and the recent proof of the practicability of their gunboats passing our batteries have made the defense of this city a very difficult problem to solve. To obstruct 2,000 yards of channel [and this with relation t the forts, Sumter and Moultrie, is decided upon as the most feasible] looks almost like an impossibility. Every effect is, however, being made to accomplish it. I am decidedly of opinion that the most effectual defense of the city of Charleston can and should be made from and around the city itself. I believe that when the enemy is prepared to assault the forts at the entrance to the harbor he will do so in such force and with such appliances as will reduce it to a question of time only. One great reliance being on these works, when they fall our means of defense will be inadequate to hold the city, but with the guns now within their walls I am satisfied to hold the city, but with the guns now within their walls I am satisfied that, however great might be the injury to the city itself from bombardment, his feet could be kept from polluting its streets. This has for some time been my opinion, and I am glad to find