History: American Civil War (1861-1865)

The one clear Confederate victory in the West was the Battle of Chickamauga. Bragg, reinforced by Lt. Gen. James Longstreet's corps (from Lee's army in the east), defeated Rosecrans, despite the heroic defensive stand of Maj. Gen. George Henry Thomas. Rosecrans retreated to Chattanooga, which Bragg then besieged.
The Union's key strategist and tactician in the West was Ulysses S. Grant, who won victories at Forts Henry and Donelson (by which the Union seized control of the Tennessee and Cumberland Rivers); the Battle of Shiloh; and the Battle of Vicksburg, which cemented Union control of the Mississippi River and is considered one of the turning points of the war. Grant marched to the relief of Rosecrans and defeated Bragg at the Third Battle of Chattanooga, driving Confederate forces out of Tennessee and opening a route to Atlanta and the heart of the Confederacy.