The Photographic History of The Civil War: in ten volumes, Thousands of Scenes Photographed 1861-65, with Text by many Special Authorities, Volume 2: Two Years of Grim War.
Francis Trevelyan Miller, Ed.

After replenishing the ammunition and adding some fresh troops, Cox advanced at three o'clock with the utmost gallantry toward Sharpsburg. The Confederates disputed the ground with great bravery. But Cox swept all before him and was at the edge of the village when he was suddenly confronted by lines in blue uniforms who instantly opened fire. The Federals were astonished to see the blue-clad battalions before them. They must be Union soldiers; but how did they get there? The matter was soon explained. They were A. P. Hill's division of Lee's army which had just arrived from Harper's Ferry, and they had dressed themselves in the uniforms that they had taken from the Federal stores.

Hill had come just in time to save Lee's headquarters from capture. He checked Cox's advance, threw a portion of the troops into great confusion, and steadily pressed them back toward the Antietam. In this, the end of the battle, General Rodman fell mortally wounded. Cox retired in good order and Sharpsburg remained in the hands of the Confederates.

Thus, with the approach of nightfall, closed the memorable battle of Antietam. For fourteen long hours more than one hundred thousand men, with five hundred pieces of artillery, had engaged in titanic combat. As the pall of battle smoke rose and cleared away, the scene presented was one to make the stoutest heart shudder. There lay upon the ground, scattered for three miles over the valleys and the hills or in the improvised hospitals, more than twenty thousand men. Horace Greeley was probably right in pronouncing this the bloodiest day in American history.

Although tactically it was a drawn battle, Antietam was decisively in favor of the North inasmuch as it ended the first Confederate attempt at a Northern invasion. General Lee realized that his ulterior plans had been thwarted by this engagement and after a consultation with his corps commanders