Tennessee regiment might be used, if necessary. If you can, have boats to transfer the troops to the right flank of the river, in case of a movement on that side. Good lookouts must be kept up, to see what is doing, to gain accurate intelligence.

R. E. LEE.

HEADQUARTERS,
Harper's Ferry, Va., May 28, 1861.

[Colonel GARNETT:]

COLONEL: I reported to you on the 26th instant, for the information of the Commander-in-Chief, that the troops under my command are observing the river from Williamsport to the Point of Rocks. I will now give what then omitted-the precise disposition of these troops:

Colonel Allen is opposite to Williamsport, thirty miles above, with his own regiment, two companies of Colonel Hill's, and a section of artillery. The position cannot be defended by such a force, the ferry at Williamport being at the vertex of a horseshoe, five or six miles in length, having another at each heel. A company of cavalry and a section of artillery guard the bridge at Shepherdstown. There are two companies of infantry, two of cavalry, and six field pieces, with their men, at the bridge at the Point of Rocks, twelve miles below, and a company of cavalry at the Berlin Bridge, half way to the Point of Rocks. Preparations have been made to break each of these two bridges and the railroad bridge here. It is more than forty miles from Williamsport to the Point of Rocks. A detachment of three hundred and fifty infantry occupies a point on the Maryland Heights, one and a half miles from the near end of the crest of the ridge, and two and a half miles from Harper's Ferry. The crest of the ridge beyond the Shenandoah is guarded by two companies of infantry.

In the present state of the river no force that could be detached from this place could prevent its passage by an enemy. In a few weeks, or even days, when fords will be numerous, an army will be necessary to guard the Potomac above, as far as the western line of Berkeley. With this point occupied, as it is, some five or six thousand men, judiciously placed between Martinsburg and the line, and a reserve of about the same force within striking distance of each, invasion would be difficult. As matters now are, the enemy can easily seize Martinsburg, in the heart of a disloyal population, and nearer than Harper's Ferry to Winchester.

If the Commander-in-Chief has precise instructions to give, I beg to receive them early. I have prepared means of transportation for a march. Should it be decided that the troops should constitute a garrison, this expense can be reduced.

Your obedient servant,

J. E. JOHNSTON.

P. S.-I submit a memorandum by Major Whiting, C. S. Engineers.