The Tennessee River is formed at the confluence of the Holston and French Broad rivers on the east side of present-day Knoxville, Tennessee. From Knoxville, it flows southwest through East Tennessee toward Chattanooga before crossing into Alabama. It loops through northern Alabama and eventually forms a small part of the state's border with Mississippi, before returning to Tennessee. At this point, it defines the boundary between two of Tennessee's Grand Divisions: Middle and West Tennessee.
The Tennessee River was explored during the period of rivalry between the French and the English for the territory west of the Appalachians, and a few small forts and posts were established on its banks. Earlier, explorers and fur traders had entered the lower course of the river from the Ohio River. Although the Tennessee served as a route for settlers moving southwestward, its role as a westward passage was negligible compared with that of the Ohio.
Originally, the Tennessee could be navigated only by flatboats. Its upper course was shallow and filled with short rapids. Its middle course, through the Cumberlands, contained whirlpools and was interrupted by Muscle Shoals (rapids, now submerged by reservoirs) in Alabama. Only its lower course was easily navigable, but the advent of the railroads in the Tennessee River valley after the 1840s kept river traffic from assuming the significance it had on other western and more easily navigated rivers.
The river’s north-flowing lower course was strategically important during the American Civil War, for its valley offered an invasion route into the western Confederacy. Part of the course downstream is paralleled by the Cumberland River. The Confederate forts Henry (on the Tennessee) and Donelson (on the Cumberland) were only 12 miles (19 km) apart. General Ulysses S. Grant’s Federal army, accompanied by gunboats, struck southward in the Tennessee River valley in February 1862. The Confederate forces fell back to Corinth, Mississippi, and the Federal troops moved almost to Tennessee state’s southern boundary, where the Battle of Shiloh (Pittsburgh Landing) was fought (April 6–7, 1862).