Lincoln's General Order No. 252

In his General Order No. 252, issued on July 31, 1863, Abraham Lincoln was addressing the differential treatment that black prisoners of war were given by the Confederate Army.  Lincoln ordered that any indignities visited upon black troops would be replicated on an equal number of Confederate POWs. 

The order read: “For every soldier of the United States killed in violation of the laws of war, a rebel soldier shall be executed,” Lincoln wrote. “For every one enslaved by the enemy or sold into slavery, a rebel soldier shall be placed at hard labor on the public works, and continued at such labor until the other shall be released and receive the treatment due to a prisoner of war.”

Black Union soldiers faced harsh consequences when captured as POWs, with Confederate policy initially maintaining that they could be tried as criminal insurrectionists in state courts, and executed as such. The Confederate Congress also proposed to re-enslave black soldiers captured—even those who had lived as free men in the North before the war. 
War, real war, amongst ourselves is very ugly business indeed.