necessities of the topography have forced upon us in this important approach to Charleston, and these (troops) so distributed and necessarily broken into fractions for the occupation of the line, the points of occupation so remote from each other, so difficult of re-enforcement (when all points are threatened, as was the case last night) from one another, that, without even one regiment or one man at any point off of the very lines themselves as a central reserve, I am profoundly anxious and uneasy lest a sudden attack upon some one of the points of this line should be overwhelming before the necessary assistance could be rendered and a foothold gained by many, which would require a large force to expel them from.

The shore line from Haskell to the Secessionville bridge, a distance of 2 miles, is defended by earth-works immediately on the creek margins, viz, Batteries Haskell, Tatom, Ryan, right and left, and Redoubt Numbers 1, with a considerable line of intervening rifle-pits or infantry works. The front of this line cannot be picketed except with boats, and these can only, to a limited extent, answer the purposes of vedettes and not pickets, for they could not hold the enemy in check; they could only give notice of his approach. These batteries are manned by artillerists, but the entire infantry support, the whole available force besides, for resisting an attack made anywhere along this line consists of the Twenty-seventh South Carolina Regiment, stationed at Legare's house, about equidistant from the several works, and numbering for duty, by the report of yesterday morning, 526 men.

It must be observed that little notice can be given of an attack by barges at night; that the land picket duty on the creek margins and the details for additional guards at night at all these works is very heavy; that a simultaneous attack upon more than one point, or feints upon several, might be made, thus diverting the attention and subdividing the strength of this small command. To re-enforce these points, or to collect troops to expel the enemy, should he have succeeded in gaining any point, drafts would have to be made upon Fort Johnson, Secessionville, or the southern lines.

Fort Johnson is over 3 miles from Haskell. It is itself liable to sudden attack without warning. Its relation to the harbor is such that little should be risked in withdrawing troops from it. Within the Fort Johnson command is embraced Batteries Glover, Haskell, Simkins, Wampler, Cheves, &c., extending along 3 miles of harbor and creek shore. Independent of the artillery the whole infantry force is the Seventh South Carolina Battalion, reporting for duty yesterday 503 men. The five companies ordered to be held in readiness to move toward Haskell would have probably reached 300 men, all that could be spared.

Secessionville is over 2 miles from Haskell. It is liable to the same condition of sudden attack, and the troops there have to picket the line from the bridge to a mile beyond Fort Lamar in the direction of Battery Island. The force of infantry at this point is 502 men. The five companies, which was a hazardous draft, called for last night would have reached 300 men.

The southern and western lines, extending from Secessionville to Pringle, and then up the Stono to Pemberton, are retired sufficiently form the water, except Pringle, to afford notice of an advance of the enemy, and pickets as strong as the command can possibly admit of are thrown to the front until they meet the enemy's pickets at Dixon's and other islands, a distance of 3 miles to the front of the works.