Batteries at High Point, at Cockpit Point, and thence down to the Chopawamsic, cannot be prevented. We may, indeed, prevent their construction on certain points, but along here somewhere the enemy can establish, in spite of us, as many batteries as he chooses. What is the remedy? Favorable circumstances, not to be certainly anticipated nor made the basis of any calculations, might justify and render successful the attack and capture of a particular battery. To suppose that we can capture all, and by new attacks of this kind prevent the navigation being molested, is very much the same as to suppose that the hostile army in our own front can prevent us building and maintaining field works to protect Arlington and Alexandria by capturing them one and all as fast as they are built. As long as the enemy is master of the other shore he can build and maintain as many batteries as he chooses. If can on Stump Neck and Budd's Ferry Point establish superior batteries to his, and it is probable we can so molest him on all points where his batteries could be effectually treated as to cause him to abandon his effort. It must be considered, however, that this is an operation costly in men and munitions. We must have numerous and powerful guns; we must have several strong field works, the location of which may have to be changed by some unexpected change in the disposition of an antagonist's batteries. I should estimate that we should require ten to twenty heavy guns on Indian Head and fifty established on the shore from opposite Cockpit Point to opposite Evansport. In the same manner, should the enemy actually succeed in establishing batteries on Whitestone Point and Mathias Point, we could counterbatter them from the opposite shores. At Mathias the shore just north of Upper Cedar Point and the bluff north of Pope's Creek furnish, at 2 miles' distance, good employment for batteries. My apprehension that the enemy will actually occupy those points is not sufficient to induce me to recommend (particularly should the timber be cut off) the construction of the necessary batteries and the inclosing field works as a preventive measure. As to counter-batteries for the portion of the river between High Point and Evansport, I would wait until the disposition and ability of the enemy seriously to molest the navigation is more fully developed before commencing.

I am, very respectfully, your most obedient,

J. G. BARNARD,

Brigadier-General and Chief Engineer.

UNITED STATES STEAMER POCAHONTAS, September 29, 1861.

Major-General McCLELLAN:

SIR: Since making the excursion down the Potomac with General Barnard I have been trying to come to some conclusion regarding the reason why the enemy should have selected Freestone Point as a site for a battery. It commands nothing; is merely an annoyance on the river and no more. It does not even prevent landing should such be desired at Occoquan Mills or below the point. I feel confident that it is merely a ruse, a blind, to draw out attention from the other points to that until they are prepared at their more important points, such as High Point, Cockpit Point, and the bluff just above Evansport, on the south side of the Quantico Creek. I consider these three points as meriting the first attention. There is one circumstance that strikes me with