Following the start of the Civil War (1861-65), Forrest enlisted as a private in the Tennessee Mounted Rifles and helped equip the unit using his own money. He soon earned a promotion to lieutenant colonel and was placed in charge of raising and training his own battalion of 650 mounted troopers. Forrest would win his first engagement later that year, when he led a surprise attack on a complement of 500 Union troops near Sacramento, Kentucky.
Forrest was next involved in heavy fighting at Fort Donelson, Tennessee, in February 1862. Despite being cornered by Union forces under General Ulysses S. Grant, Forrest refused to surrender along with General Simon Bolivar Buckner and the fort’s 12,000 other Confederates. Shortly before Grant claimed the fort, Forrest led roughly 700 cavalry past the Union siege lines and escaped to Nashville, where he coordinated evacuation efforts. Forrest was heavily engaged at the Battle of Shiloh in April 1862 and commanded rearguard actions during the Confederate retreat into Mississippi. Already known for his daring, Forrest reportedly led a cavalry charge against Union skirmishers and singlehandedly engaged several troops despite sustaining a gunshot wound to the back. His legend would continue to grow after the battle, when he published a recruiting notice in a Memphis newspaper that included the line “Come on boys, if you want a heap of fun and to kill some Yankees.”
Forrest’s injury would keep him away from the field until June 1862. A month later he led a raiding mission into Tennessee, where he captured a Union garrison at Murfreesboro. Promoted to brigadier general, Forrest next participated in cavalry operations near the vital Mississippi River hub at Vicksburg, Tennessee, which was under siege by Ulysses S. Grant. Throughout late 1862 and early 1863, Forrest’s cavalry relentlessly harassed Grant’s forces, frequently cutting off communication lines and raiding stores of supplies as far north as Kentucky. Careful to never engage the superior Union numbers in outright combat, Forrest instead relied on guerilla tactics designed to frustrate and exhaust his pursuers.
Forrest was engaged throughout early 1863 in operations near Fort Donelson and at the Battle of Thompson’s Station. In May 1863 he successfully cornered Union cavalry commanded by Colonel Abel Streight near Cedar Bluff, Alabama. Recognizing that Streight held a substantially larger force, Forrest led his troopers around the same hilltop multiple times in order to give the appearance of larger numbers. He then bluffed Streight into surrendering his 1,500 Union cavalry before revealing he had less than a third as many men.
Forrest was prominent during the Battle of Chickamauga in September 1863, in which part of his cavalry dismounted and fought alongside infantrymen on the Confederate right flank. He was then instrumental in pursuing the retreating Union army. After the battle Forrest openly criticized General Braxton Bragg, who he believed had failed to capitalize on the Confederate victory. Frustrated with his commanding officer, Forrest requested a new assignment, and in October 1863 he was placed in independent command in Mississippi. Promoted to major general in December 1863, Forrest fought a series of small engagements in Tennessee before defeating a much larger Union force at the Battle of Okolona in February 1864.
Forrest’s most controversial action as a field commander would come in April 1864 at the Battle of Fort Pillow in Tennessee. After capturing the federal garrison by force, Forrest’s men reportedly killed over 200 Union soldiers, many of them black troops who had formerly been slaves. While Forrest and his men would claim the fort’s occupants had resisted, survivors of what became known as the “Fort Pillow Massacre” argued that Forrest’s men had ignored their surrender and murdered dozens of unarmed troops. The Joint Committee on the Conduct of War would later investigate the incident and agree that Forrest’s men had committed an unjust slaughter.
His reputation stained by the events at Fort Pillow, Forrest went on to achieve a stunning victory in June 1864 at the Battle of Brice’s Crossroads. After leading nearly 8,500 Union troops on an exhausting chase, Forrest counterattacked with 3,500 men near Baldwyn, Mississippi, destroying the Union force and claiming valuable supplies and arms. Forrest then suffered a defeat at the hands of William T. Sherman’s forces at the Battle of Tupelo in July 1864. He would respond with raids against Memphis and Johnsonville, Tennessee, before linking up with forces under General John Bell Hood in November 1864. Forrest participated in the Confederate defeat at the Second Battle of Franklin before suffering another loss at the Third Battle of Murfreesboro in December. After Hood’s beleaguered Army of Tennessee was routed at the Battle of Nashville, Forrest led rearguard operations during the retreat into Mississippi.
Promoted to lieutenant general in February 1865, Forrest would oppose Union General James H. Wilson during his raid into the Deep South but was defeated at the Battle of Selma in April 1865. He then disbanded his weakened force in May 1865 following the surrender of the Confederacy’s major armies.