In 1862, Lincoln plays a military masterstroke. He issues the Preliminary Emancipation Proclamation. This is an ultimatum to the South to surrender. If it does, slavery will still be allowed in those Southern States who lay down their arms. Despite its conciliatory tone, it energises the Union troops and encourages slave desertions in the South. This further cripples the cotton economy of the Confederacy already suffering from having to grow food for the war effort. Historian Howard Zinn estimates that one in five slaves escape during the Civil War and many boosted Union ranks by joining as soldiers. In all, 200,000 blacks join up and 38,000 will give their lives. Montgomery Meigs, an advocate of blacks becoming soldiers, is particularly pleased to see newly uniformed blacks acting as prison guards to the rebellious confederates.
But the black issue is still so contentious, that Lincoln, ever the politician, prepares in December 1862 for 'colonisation'. This is the removal of the blacks onto various islands as an alternative to incorporating blacks as equals in America. But this option isn't implemented because the South doesn't capitulate. And so, on New Year's Day, 1863, Lincoln signs the final Emancipation Proclamation and frees the slaves. There will be no more compromises.
In September, yet another Union General fails to live up to earlier promise and loses the battle of Chickamauga. His remaining force is laid siege to at Chattanooga. Victory is snatched back by the ever accommodating Meigs who resupplies the starving soldiers and by the relieving Generals Grant, and William Sherman. And it's this ability to mobilise forces immediately that explain how the Confederates could win virtually every battle, but lose the war.