Our strength at Sharpsburg.  I think this is correct: 

Jackson (including A.P.  Hill) 10,000

Longstreet 12,000

D.H.  Hill and Walker                    7,000
______
Effective infantry                      29,000

Cavalry and artillery                    8,000
______
Total of all arms                       37,000

This disproportion was very great, amounting, as it did, to more than two for one.  But this was unavoidable.  The Southern army had been worn out by their long marching and fighting.  Portions of the command were scattered all over the roads of Northern Virginia, wearily dragging their half-clothed limbs and shoeless feet toward Winchester, whither they were directed to repair.  This was the explanation of the fact that, in spite of the ardent desire of the whole army to participate in the great movement northward, Lee had in line of battle at Sharpsburg “less than forty thousand men.”

General McClellan made a demonstration against his adversary on the evening of the 16th, before the day of the main struggle.  He threw his right, commanded by General Hooker, across the Antietam at a point out of range of fire from the Confederates, and made a vigorous attack on Jackson’s two divisions lying near the Hagerstown road running northward, and thus parallel with Lee’s line of battle.  A brief engagement took place in the vicinity of the “Dunker Church,” in a fringe of woods west of the road, but it was too late to effect any thing of importance; night fell, and the engagement ceased.  General Hooker retaining his position on the west side of the stream.

The opposing lines then remained at rest, waiting for the morning which all now saw would witness the commencement of the more serious conflict.

V.

THE BATTLE OF SHARPSBURG.

The battle of Sharpsburg, or Antietam, for it is known by both names, began at early dawn on the 17th of September.

General McClellan had obviously determined to direct his main assault against the Confederate left, a movement which General Lee had foreseen and provided for,[1] and at dawn commenced a rapid fire of artillery upon that portion of the Confederate line.  Under cover of this fire, General Hooker then advanced his infantry and made a headlong assault upon Jackson’s line, with the obvious view of crushing that wing of Lee’s army, or driving it back on Sharpsburg and the river.  The Federal force making this attack, or advancing promptly to support it, consisted of the corps of Generals Hooker, Mansfield, and Sumner, and numbered, according to General Sumner, forty thousand men, of whom eighteen thousand belonged to General Hooker’s corps.

[Footnote 1:  “In anticipation of a movement to turn the line of Antietam, Hood’s two brigades had been transferred from the right to the left,” etc.—­Lee.]