The Twenty-seventh Texas Cavalry, organized in March of 1862, was a conglomerate of new companies added to four preexisting units from the Fourth Texas Cavalry Battalion. The regiment was also known as Whitfield's Legion and the First Texas Legion but was not a combined arms unit like other Civil War legions. With twelve companies lettered A to L, the regiment comprised primarily East Texas volunteers from Hunt, Hopkins, Jackson, Jasper, Lamar, Lavaca, Morris, Red River, San Augustine, and Titus counties. Company K of the Twenty-seventh contained soldiers from Arkansas. Col. John Wilkins Whitfield was promoted to major in March 1862 to serve as commander of the regiment. He was promoted to brigadier general on May 9, 1863, and stayed in the field until fall 1864. His staff officers included Maj. John T. Whitfield, Lt. Col. Edwin R. Hawkins, and Lt. Col. John H. Broocks. After Whitfield's promotion to brigadier general, Hawkins was promoted to colonel and assumed command of the regiment until the end of the war.
Although organized in Texas, the Twenty-seventh Cavalry saw most of its action east of the Mississippi River. It served as a dismounted unit until fall 1862 but was remounted for the remainder of the war. On March 6–8, 1862, the regiment took part in the battle at Pea Ridge (Elkhorn Tavern) in Northwest Arkansas near the city of Garfield. On April 29, 1862, the Twenty-seventh Cavalry was assigned to the Second Brigade, Price's Division, in the Army of the West (the Army of West Tennessee) and saw action in Mississippi from September 1862 to May 1864. While in Mississippi the regiment took part in the battle at Iuka on September 19, 1862, and the battle of Corinth on October 3–4, 1862. It was also engaged in several skirmishes around the towns of Jackson, Utica, Brownsville, Yazoo City, and Grand Gulf. The Twenty-seventh Texas Cavalry was transferred to the Atlanta campaign on May 15, 1864, where it served until September 8 that same year. From September 29 to November 3, 1864, the regiment took part in Gen. John Bell Hood's Operations in Northern Georgia and Northern Alabama. From November 22, 1864, to December 25 of that year, the regiment saw action in parts of Tennessee. At war's end the Twenty-seventh Texas Cavalry was on duty near Iuka, Mississippi, and officially surrendered on May 4, 1865, along with troops from the Department of Alabama, Mississippi, and East Louisiana. Men from the regiment were paroled later in May of 1865 at the towns of Meridian and Corinth, Mississippi.