Battle of Shiloh in the context of "James A. Garfield"

The American Civil War significantly affected Tennessee, with every county witnessing combat. During the War, Tennessee was a Confederate state, and the last state to officially secede from the Union to join the Confederacy. Tennessee had been threatening to secede since before the Confederacy was even formed, but would not officially do so until after the fall of Fort Sumter when public opinion throughout the state drastically shifted. Tennessee seceded in protest to President Lincoln's April 15 Proclamation calling forth 75,000 members of state militias to suppress the rebellion. Tennessee provided the second largest number of troops for the Confederacy, and would also provide more southern unionist soldiers for the Union Army than any other state within the Confederacy.

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 then little-known Ulysses S. Grant, while his area commander Henry Halleck was rewarded with a 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 afterward. At Nashville in December 1864, George Thomas routed the Army of Tennessee under John Bell Hood, the last major battle fought in the state.

William Tecumseh Sherman (/tɪˈkʌmsə/ tih-KUM-sə; February 8, 1820 – February 14, 1891) was an American soldier, businessman, educator, and author. He served as a general in the Union Army during the American Civil War (1861–1865), earning recognition for his command of military strategy but criticism for the harshness of his scorched-earth policies, which he implemented in his military campaign against the Confederate States. British military theorist and historian B. H. Liddell Hart declared that Sherman was "the most original genius of the American Civil War" and "the first modern general".

Born in Lancaster, Ohio, into a politically prominent family, Sherman graduated in 1840 from the United States Military Academy at West Point. In 1853, he interrupted his military career to pursue private business ventures, without much success. In 1859, he became superintendent of the Louisiana State Seminary of Learning & Military Academy, now Louisiana State University, but resigned when Louisiana seceded from the Union. Sherman commanded a brigade of volunteers at the First Battle of Bull Run in 1861, and then was transferred to the Western Theater. He was stationed in Kentucky, where his pessimism about the outlook of the war led to a breakdown that required him to be briefly put on leave. He recovered and forged a close partnership with General Ulysses S. Grant. Sherman served under Grant in 1862 and 1863 in the Battle of Fort Henry and the Battle of Fort Donelson, the Battle of Shiloh, the campaigns that led to the fall of the Confederate stronghold of Vicksburg on the Mississippi River, and the Chattanooga campaign, which culminated with the routing of the Confederate armies in the state of Tennessee.

Braxton Bragg (March 22, 1817 – September 27, 1876) was an American military officer during the Second Seminole War and Mexican–American War. He later served as a Confederate general in the American Civil War, seeing action in the Western Theater. His most important role was the commander of the Army of Mississippi, later renamed the Army of Tennessee, from June 1862 until December 1863.

Bragg, a native of Warrenton, North Carolina, was educated at West Point and became an artillery officer. He served in Florida and then received three brevet promotions for distinguished service in the Mexican–American War, most notably the Battle of Buena Vista. He resigned from the U.S. Army in 1856 to become a sugar plantation owner in Louisiana. At the start of the Civil War, Bragg trained soldiers in the Gulf Coast region. He was a corps commander at the Battle of Shiloh, where he launched several costly and unsuccessful frontal assaults but nonetheless was commended for his conduct and bravery.

Major-General Patrick Ronayne Cleburne (/ˈkleɪbɜːrn/ KLAY-burn; March 16, 1828 – November 30, 1864) was a senior officer in the Confederate States Army who commanded infantry in the Western Theater of the American Civil War.

Born in Ireland, Cleburne served in the 41st Regiment of Foot of the British Army after failing to gain entrance into Trinity College of Medicine, Dublin in 1846. He served at Fort Westmorland on Spike Island and was present on the island in 1849 when Queen Victoria visited Cork Harbour. Three years after joining the Army, he immigrated to the United States. At the beginning of the American Civil War, Cleburne sided with the Confederate States. He progressed from being a private soldier in the local militia to a division commander. He participated in many military campaigns, especially the Battle of Stones River, the Battle of Missionary Ridge and the Battle of Ringgold Gap. He was also present at the Battle of Shiloh. Known as the "Stonewall of the West", Cleburne was killed leading his men at the Battle of Franklin.