that although your
corps was ordered to be in a designated position at 12 M. to-day, at
or near sunset only one division and four batteries had reached the
ground intended for your troops. The general has also been advised
that there was a delay of some four hours in the movement of your
command yesterday. I am instructed to call upon you for explanations
of these failures on your part to comply with the orders given you,
and to add, in view of the important military operations now at
hand, the commanding general cannot lightly regard such marked
departure from the tenor of his instructions.

I am, general, very respectfully, your obedient servant,

----------,

Lieutenant-Colonel, Aide-de-camp, and Act'g Ass't Adj't. Gen'l."

To this missive Burnside dictated the following answer on the field
during the battle:--[Footnote: Official Records., vol. xix. pt. ii.
p. 314.]

"HEADQUARTERS, September 17, 1862.

BRIG. GEN. S. WILLIAMS, Assistant Adjutant-General.

GENERAL,--Your dispatch of yesterday this moment received. General
Burnside directs me to say that immediately upon the receipt of the
order of the general commanding, which was after twelve o'clock, he
ordered his corps to be in readiness to march, and instead of having
Captain Duane [Footnote: Captain Duane was senior engineer officer
in the field, on the staff of McClellan, and had conducted the
reconnoitring of the Antietam.] post the divisions in detail, and at
the suggestion of Captain Duane, he sent three aides to ascertain
the position of each of the three divisions, that they might post
them. These aides returned shortly before three o'clock, and they
immediately proceeded to post the three columns. The general then
went on an eminence above these positions to get a good view of
them, and whilst there, during the progress of the movement of his
corps, an aide from General McClellan came to him and said that
General McClellan was not sure that the proper position had been
indicated, and advised him not to hasten the movement until the aide
had communicated with the general commanding. He (General Burnside)
at once went to General McClellan's headquarters to inform him that
he had seen large bodies of the enemy moving off to the right. Not
finding the general commanding, General Burnside returned to his
command, and the movement was resumed and continued as rapidly as
possible. General Burnside directs me to say that he is sorry to
have received s