In 1860, the election of anti-slavery candidate Abraham Lincoln cause the division between North and South to boil over. Thirteen states from the South seceded and formed the Confederate States of America.
After disaster occurs for the North at the Battle of Shiloh, Grant seizes the opportunity to counterattack and defeats the South leading them to retreat. The counterattack ends what is considered the South's best opportunity for victory.
The The Emancipation Proclamation changes the North's goal from preservation of the Union to ending slavery. Grant's victory at Vicksburg, Mississippi allows him to move on Chattanooga, Tennessee and strike at the heart of the South's war-transportation system.
The Battle of Chickamauga becomes the second deadliest in the war. After a decisive loss for the North, Grant is placed in charge of the Union Army. Grant plans an offensive deep into the Confederacy that becomes know as the death knell of the Confederacy.
By early 1864, General William Tecumseh's army is marching from Chattanooga to Atlanta. Nonetheless, Lincoln appears to be on the verge of losing the presidential election, until Tecumseh captures Atlanta.