In February 1862, some of the war's first serious fighting took place along the Tennessee and Cumberland rivers, recognized as major military highways, and mountain passes such as Cumberland Gap were keenly competed-for by both sides. The Battle of Shiloh and the fighting along the Mississippi brought glory to the little-known Ulysses S. Grant, while his area commander Henry Halleck was rewarded with promotion to General-in-Chief. The Tullahoma campaign, led by William Rosecrans, drove the Confederates from Middle Tennessee so quickly that they did not take many casualties, and were strong enough to defeat Rosecrans soon afterwards. At Nashville in December 1864, George Thomas routed the Army of Tennessee under John Bell Hood, the last major battle fought in the state.