The Battle of Antietam was fought in Washington County, Maryland on September 16 – 18, 1862.
It would be the bloodiest day of the entire Civil War.
Battle of Antietam Timeline
17 September: The Battle of Antietam (also known as Sharpsburg). It must be pointed out that the exact timing of events at Antietam are, to some extent only approximate. There were a vast number of watches on the field, with no common standard. Dawn, which is listed for 17 September at 5:43 AM, Major General Hooker’s Federal I Corps begins advance into the north woods with the divisions of Doubleday and Ricketts. The action against Stonewall Jackson’s Confederate divisions commanded by Lawton and D. R. Jones commences at approximately 6:15 AM.
7:00 AM: Brigadier General John Hood’s Confederate Division counter-attacks Hooker’s forces; bitter fighting in the cornfield and in the east woods.
7:20 AM: Hood’s assault is repulsed; Federal XII Corps arrives on the field, deploying into the east woods by 7:30 AM.
8:30 AM: Major General Edwin Sumner brings Sedgwick’s division of Federal II Corps into the east woods; severe fighting continues.
9:00 AM: Federal I and XII Corps are fought out by now; French’s division of Federal II Corps arrives opposite the sunken road position, ultimately supported by Richardson’s Division of II Corps. Fighting dies out on the Confederate left by 10:30 AM.
9:30 AM: Federal II Corps divisions of French and Richardson begin to assault the sunken road position in the Confederate center held by Major General D. H. Hill’s division. There is a great deal of bloody fighting until the position is finally taken by Federal forces at 1:00 PM, and then there is little subsequent activity at the Confederate center. Meanwhile in the south, Major General Ambrose Burnside has received several orders, at least from 10:00 AM, to assault the bridge to his front. The stone bridge is finally taken by elements of Sturgis’s division of Federal IX Corps at 1:00 PM. The remainder of the Federal IX Corps is across Antietam Creek and advancing towards Sharpsburg by 3:00 PM.
3:45 PM: The Confederate division commanded by Major General Ambrose Powell Hill begins arriving on the field, after completing a seventeen mile march from the Harper’s Ferry area. Hill’s division counter-attacks Federal IX Corps, the action completed by 4:30 PM.
There is no further activity of significance anywhere on the field.
18 September: Robert E. Lee and the Army of Northern Virginia begins crossing back over the Potomac River into Virginia near Shepherdstown, West Virginia. The operation is completed on 19 September.
Source: The History Reader