Fort Henry, situated on the Tennessee River, was a linchpin in Confederate General Albert Sidney Johnston (Johnston, Albert Sidney)'s defense lines. Along with Fort Donelson (Fort Donelson, Battle of) on the Cumberland River, Fort Henry bisected Southern lines and guarded rich mineral deposits and agricultural lands as well as the important city of Nashville, Tennessee. Union General Henry Halleck (Halleck, Henry W) hoped to regain control of western rivers as a means of piercing Confederate defenses, and in early February 1862 he sent General Ulysses S. Grant (Grant, Ulysses S.) and Commodore Andrew Foote (Foote, Andrew) on a joint endeavour to capture Forts Henry and Donelson. A Union force of 15,000 men and seven gunboats traveled along the Tennessee to Fort Henry, whose meagre defenses they overcame on February 6. About 2,500 Confederate defenders under General Lloyd Tilghman fought briefly, then retreated 12 miles (19 km) overland to nearby Fort Donelson to prepare a stronger defensive line.

The Union victory was largely the result of a fierce gunboat bombardment, as Grant's men had arrived too late to see action. The victory cost the North 11 killed and 31 wounded; Southern losses totaled 5 killed, 11 wounded, and 78 prisoners of war. The battle's consequences were greater than its size, however. Navigation on the upper Tennessee fell to the Union, and Fort Donelson on the Cumberland River then stood alone guarding the Confederacy's western heartland and population centres.