Company K was formed from men primarily in the southern half of DeSoto County. The 1860 Census shows many of them living around Senatobia, Elm Grove, and Looxahoma, though some members were from Hernando and Cockrum. The unit apparently was formed sometime in 1863.

The Fifth Mississippi Cavalry was originally commanded by Colonel James Z. George and is first mentioned in General Chalmers' report of operations preceding the raid on Colliersville in October 1863. Chalmers wrote that when he moved from Oxford to Salem on October 5th, he left "the new regiment, commanded by Colonel George, which was not fully organized, to picket the river." On October 22 Chalmers reported the Fifth was 350 strong. "Colonel George's regiment of cavalry" was assigned to Slemon's Brigade of Chalmer's command on October 18, 1863.

On November 3, 1863, Chalmer's made a second attempt at Collierville, Tennessee in which the Fifth participated. The Fifth was part of the assault on a position held by two pieces of artillery. Chalmers reported his loss as 6 killed, 63 wounded, 26 prisoners. "Among the last Col. J. Z. George and my Chief Surgeon, Dr. William H. Beaty. Colonel George led the charge made by Slemons' Brigade and rode into the town, followed by Captain Scales and Lieutenant Lamkin of his regiment and a few of his men." The other casualties of the regiment were 4 killed and 14 wounded.

Early in December 1863 the regiment participated in another raid against the railroad, Chalmers' command cooperating with the movements of Generals S. D. Lee and Forrest. One company of the Fifth was in the gallant fight made at the Wolf River bridge on December 4^th by Colonel McCulloch.

The Fifth cavalry under Col. James Z. George was listed as part of Slemons' Brigade of Chalmers' Division, in the organization of cavalry under Maj.-Gen. S. D. Lee in January, 1864. General Forrest brigaded the regiment under Col. Jeff E. Forrest. The regiment was with General Forrest in the Okolona, Mississippi campaign of February 1864, which resulted in the defeat of Gen. Sooy Smith's expedition from Memphis, at the time General Sherman advanced from Vicksburg to Meridian. In the desperate fight about five miles from Okolona, February 22 the casualties of the regiment were 3 killed, 3 wounded, 3 missing. The regiment was with Chalmers and Forrest in the famous Tennessee raid of March and April 1864, including the attack on Fort Pillow on April 12^th. In the engagements between Pontotoc and Tupelo, Mississippi July 10-15, 1864, including the battle of Harrisburg, the Fifth had 5 killed, 7 wounded.

The regiment was with Wade's Brigade in August 1864 contesting the advance of Hatch's Federal Division to Oxford. They skirmished with the raiders in front of Oxford, and on the 23^rd attacked the retreating column at Abbeville, where the Fifth fought dismounted and lost 4 killed, 10 wounded, and 12 missing.

General Chalmers advanced within five miles of Memphis, October 8, 1864 but finding no opportunity for surprise, moved into West Tennessee with his escort and the Fifth Regiment. The Fifth, along with Chalmers' command, joined General Forrest in Florence, Alabama. They crossed the Tennessee River at Florence November 17, 1864, and remained several days on Shoal Creek, during which time they had several skirmishes, part of their wagon train being taken and retaken. They began the march north November 21, and on the 23d fought Capron's Brigade at Henryville, capturing 65 prisoners. They skirmished about Columbia until the evacuation November 28^th then moved toward Franklin and struck the head of the Federal column toward Spring Hill. They took part in the assault of the Federal position at Franklin, Tennessee on November 30^th, in which the casualties of the Fifth were 2 killed and 8 wounded.

On December 3 Rucker's Brigade, including the Fifth, took position on the Hillsboro Pike near Nashville. On December 14^th Chalmers and Rucker, with Ector's Brigade, held a line of about four miles with 900 men. The Federal attack of the 15th opened up the Harding pike and Chalmers' ordnance train was taken, the Federals advancing in his rear. Rucker had been lighting a gunboat on the river and cavalry on the Charlotte pike, but his men made good their retreat and were cut off from the army until the 16^th. They then received orders to move promptly to Brentwood where they rendered valuable services in protecting the wagon trains. In the evening of the 16^th Rucker's Brigade fought desperately until after dark, when they were driven toward the Franklin Pike. Rucker was wounded and captured in the hand-to-hand struggle. The loss of these two days was heavy. The remnant of the brigade was with Forrest and the rear guard on the retreat to the Tennessee River.

In February 1865 Companies C, D, E, H, K, Fifth Mississippi Cavalry, with Lieut.-Col. A. H. Chalmers, were assigned to Starke's Brigade. In an order dated March 16, 1865 General Chalmers said, "There being no field officers of the Fifth Mississippi Cavalry present and able for duty and only two companies of that regiment having 32 men present, the companies composing that regiment and not included in this order (consolidating E, H and K with Chalmers' Battalion), have been consolidated with other companies and regiments from the same State." On May 7, 1865 Federal Gen. J. H. Wilson ordered an officer sent to Forsyth, Georgia to receive the surrender of the Fifth Mississippi Cavalry.

Below is a roster of men who served in Company K extracted from the Civil War Soldiers and Sailors System of the National Park Service. Because the same soldier was sometimes listed more than once due to variations in spelling his name, the total number given is inflated. The listing has not been changed because there is no way to determine where these spelling errors have occurred.