Although slaves were numerous in W Tennessee, and to a lesser extent in Middle Tennessee, and free blacks were subjected to a series of discriminatory regulations, the state was pro-Union; it voted in the presidential election of 1860 for its own John Bell, candidate of the moderate Constitutional Union party. Secession was rejected in a popular referendum on Feb. 9, 1861. However, after the firing on Fort Sumter and Lincoln’s call for troops, the pro-Confederate element, led by Gov. Isham G. Harris, canvassed the state, and on June 8, 1861, a second referendum approved secession by a two-thirds majority. The one third opposed represented mainly E Tennessee, where slavery was a negligible factor and where Andrew Johnson (then U.S. Senator) and William G. Brownlow had strengthened the natural Union loyalties of the people.
In the Civil War Tennessee was, after Virginia, the biggest and bloodiest battleground. The rivers served as Union invasion routes. Nashville was occupied by Gen. D. C. Buell in Feb., 1862, after the victories of Gen. Ulysses S. Grant on the lower Tennessee and Cumberland rivers. In April one of the bloodiest battles of the war was fought near the Mississippi state line, and Memphis fell to a Union fleet in June. Confederate Gen. Braxton Bragg, defeated at Perryville, Ky. in Oct., 1862, retreated further in Jan., 1863, after the battle of Murfreesboro, and Grant, successful in the Vicksburg campaign, completely routed him (Nov., 1863) in the Chattanooga campaign.
The Confederates did manage to hold on to Knoxville until Sept., 1863, and their cavalry, particularly the forces of Gen. N. B. Forrest and Gen. J. H. Morgan, remained active. An army under Gen. J. B. Hood made a last desperate attempt to regain the state late in 1864 but was defeated at Franklin (Nov. 30) and annihilated at Nashville (Dec. 15–16) by federal troops under G. H. Thomas. The Union military government that had been set up under Andrew Johnson in 1862 was succeeded in Apr., 1865, by a civil government headed by Brownlow. An amendment to the state constitution of 1834 freed the slaves, and, with ex-Confederates disfranchised and radical Republicans in control, the state was readmitted to the Union in Mar., 1866.
As the first Confederate state to be readmitted, Tennessee was spared the worst aspects of Congressional Reconstruction, but the postwar years were nonetheless bitter. The organization formed largely to reestablish “white supremacy” in the South, the Ku Klux Klan, was founded (1866) in Tennessee, at Pulaski. The situation improved after Brownlow left (1869) the governorship for the U.S. Senate, to which the state also returned (1875) Andrew Johnson in vindication of his record as Lincoln’s successor in the presidency. Brownlow’s successor, Gov. De Witt C. Senter, although nominally a Republican, encouraged the calling of a new state constitutional convention. In 1870 the delegates drew up a constitution that rejected the reforms of the radical Republicans; African-American suffrage was limited by means of the poll tax and former Confederates were reenfranchised.