Unknown to R. Patterson, U.s. A., Hagerstown, Md, June 20, 1861

General R. PATTERSON, U.S. A., Hagerstown, Md.:

I desire you to cause to be examined the Maryland Heights, overlooking Harper’s Ferry, with a view to a battery sufficient to hold the same, and also without delay to propose to me a plan of operations with a portion of your force to sweep the enemy from Leesburg towards Alexandria, in co-operation with a strong column from this end of the same road. Of course it is designed that you should absorb the column of Colonel Stone, now covering the fords and ferries on the Potomac below Leesburg; the remainder of your troops (how many ?) to be left to cover the detachment on the Maryland Heights. Reply promptly.

(Copy to General McDowell.)