September 15, 1862 (Monday): "Destroy the rebel army if possible".

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Colonel R. H. CHILTON.
NEAR 8 A. M. September 15, 1862
    GENERAL: Through God's blessing, Harper's Ferry and its garrison are to be surrendered. As Hill's troops have borne the heaviest part in the engagement, he will be left in command until the prisoners and public property shall be disposed of, unless you direct otherwise. The other forces can move off this evening so soon as they get their rations. To what point shall they move? I write at this time in order that you may be apprised of the condition of things. You may expect to hear from me again to-day after I get more information respecting the number of prisoners, &c.
    Respectfully,


    T. J. JACKSON
    Major-General.

Washington, September 15, 1862-2.45 p.m.
Major-General McCLELLAN:
    Your dispatch of to-day received. God bless you and all with you.
     Destroy the rebel army if possible.


    A. LINCOLN.

Official Records, Series I., Vol. 19, Part 1, Page 53.

The destruction of an army, which Lincoln desires McClellan to achieve, was not easy to accomplish.  However, this was a rare opportunity to do just that.  Lee's army had lost heavily at South Mountain, Hill was at Harper's Ferry paroling Union prisoners, and the main body of Confederate forces was greatly reduced by straggling.