President Lincoln’s Emancipation Proclamation was issued on January 1, 1863.
From Embattled Rebel: Jefferson Davis as Commander in Chief, by James M. McPherson (Penguin, 2014), Kindle Loc. 1796-1812:
On January 12, 1863, the [Confederate] president [Davis] issued a proclamation stipulating that captured officers and men of black Union regiments would be turned over to states to be tried for inciting or participating in slave insurrections. Congress enacted legislation endorsing this policy but substituting military courts for state courts. This change would have made no difference in the likely punishment—execution. But carrying out this policy proved to be impracticable. Union secretary of war Edwin M. Stanton ordered all exchanges of Confederate officers stopped so they could be held as hostages for retaliation if the Confederacy executed Northern officers. The Davis administration decided to restore captured ex-slave soldiers to bondage instead of putting them to death—though in fact many were killed by enraged Southern soldiers rather than allowed to surrender. “Captured slaves should be returned to their masters” if they could be found, Davis informed one Confederate general. “Until such time, they might be usefully employed on public works.”
On July 30, 1863, Abraham Lincoln issued an “Order of Retaliation” stating that for every Union captive executed, a Confederate prisoner should be treated likewise; for every captive reenslaved, a Confederate prisoner would be placed at hard labor on public works. This order was effective in preventing the official (but not unofficial) killing of black prisoners and their officers. But it did not completely stop reenslavement, because few Southern prisoners were remanded to hard labor in retaliation. The Confederates refused to exchange black soldiers under the exchange cartel negotiated in 1862. This refusal caused exchanges to cease, and the prisons of both sides began the descent toward overcrowding and tragic mortality that debased the last eighteen months of the war.
From Embattled Rebel: Jefferson Davis as Commander in Chief, by James M. McPherson (Penguin, 2014), Kindle Loc. 2125-42:
The apparent stalemate in front of Atlanta compounded the sense of futility and failure that spread through the North in the summer of 1864. Grant had bogged down before Petersburg and Richmond after the Army of the Potomac suffered sixty thousand casualties in two months with little to show for all the carnage. “Who shall revive the withered hopes that bloomed at the beginning of Grant’s campaign?” asked a New York newspaper on July 12.
Northern war weariness revived the prospects of Copperhead Democrats, who hoped to nominate a peace candidate for president and defeat Lincoln’s reelection. A clamor for negotiations with the Confederacy became insistent. Lincoln had no faith in such a parley. He was running for reelection on a platform calling for “unconditional surrender” by the Confederacy and an amendment to the Constitution to abolish slavery in a restored Union. But the United States president could not ignore the pressure for peace. When Confederate agents in Canada convinced New York Tribune editor Horace Greeley that they were empowered to open negotiations, Greeley in turn pressed Lincoln to respond. He did so, specifying Union and emancipation as preconditions for any such negotiations. This proviso gave Confederates a propaganda victory by enabling them to accuse Lincoln of sabotaging the chance for peace by laying down conditions he knew were unacceptable to the Confederacy. So long as the war seemed to be going badly for the North—as it did in July and August 1864—this impression dimmed the prospects for Lincoln’s reelection.
Jefferson Davis had no more faith that negotiations could achieve peace with independence for the Confederacy than Lincoln believed they could achieve peace with reunion. But while Davis did not have to face a reelection campaign, he too was subject to pressure from Southerners who longed for peace. Vice President Alexander Stephens led an informal coalition that urged Davis to cultivate Northern Peace Democrats by agreeing to negotiations without insisting on Confederate independence as a precondition. Davis rejected this approach. Since independence would be an ultimate goal of negotiations, he maintained, it would be dishonest and useless to pretend otherwise.