Abraham Lincoln's Emancipation does not only free slaves in the rebelling states. It changes the war from one of reunification, to one of ending slavery. The Emancipation Proclamation also gives African Americans freedom to fight. By war's end, some 200,000 will enlist. In truth, Lincoln's proclamation is an empty promise without the power of the United States Army to enforce it. In 1863, Ulysses S. Grant begins a campaign to take Vicksburg, Mississippi, a Confederate citadel overlooking a strategic section of the lower Mississippi River. In May, Grant begins laying siege to the city of 4500. Mary Loughborough is one of the many terrified civilians who have dug caves into the hillsides for protection. Clutching her 2-year old daughter, Mary "endeavored by constant prayer to prepare myself for the sudden death I was almost certain awaited me." On July 4, 1863 – the day after Pickett's disastrous charge at Gettysburg – the Confederates surrender Vicksburg to Grant. With the Mississippi River now under Union control, the campaign moves eastward to Chattanooga, Tennessee, a rail center that Lincoln considers to be as important as the Confederate capital of Richmond. Eight miles south, along the Chickamauga - a creek the Cherokee call "the river of death" - Union and Confederate forces clash in what will become the biggest battle of the Western Theater.