The Eighteenth Texas Infantry was organized during the summer and fall of 1862, specifically May 13, 1862, in Jefferson, Texas, in Marion County. The entire career of the Eighteenth was spent within the Trans-Mississippi Department, and the regiment had up to eleven companies and participated in more than twenty military engagements. The Eighteenth was also known as Ochiltree's regiment.
The eleven companies of the Eighteenth Texas Infantry were: Company A from Cherokee County commanded by Capt. Matthew A. Gaston; Company B from Rusk and Marion counties commanded by Capt. R. Z. Buckner; Company C from Rusk and Cherokee counties commanded by Capt. Thomas R. Bonner; Company D from Jefferson and Marion counties commanded by Capt. John K. Cocke; Company E known as the Grayrock Volunteers from Sulphur Springs, Hopkins County, commanded by Capt. Richard Keningham; Company F from Homer, Angelina, and Titus counties commanded by Capt. Joseph G. W. Wood; Company G from Rusk County commanded by Capt. J. Dansby; Company H from Coffeeville, Upshur County, commanded by Capt. J. W. Duncan; Company I from Shelbyville, Shelby, and Rusk counties commanded by Capt. W. W. Thompson; Company K from Jacksonville, Cherokee County, commanded by Capt. W. H. Lovelady; Company L commanded by Capt. James McKnight.
During late 1862 a detachment of the unit was temporarily mounted and ordered south of the Rio Grande into Mexico, where a large herd of cattle had been purchased for the Confederacy. The detachment brought these cattle back across the Rio Grande to Central Texas. In October 1862 a new division was formed, and the Eighteenth Texas Infantry was incorporated into the First Brigade. In December, John G. Walker assumed command of the division, and the division was later known as "Walker's Greyhounds" denoting its many long, forced marches back and forth across Louisiana and Arkansas. In January 1863 the division was sent to the Arkansas Post, located on the Arkansas River near the Mississippi River, to assist in its defense. They arrived too late to help. They were sent on two long marches—one via the Red River to counter Gen. Nathaniel Banks in Alexandria, Louisiana, and one to Perkins Landing, fifteen miles from Vicksburg. Both times they arrived too late, and their participation was limited to skirmishing with several Union gunboats.
The Eighteenth saw action on June 7, 1863, at Milliken's Bend, Louisiana, with 184 casualties, including two officers killed. They again saw action on June 15, 1863, at Richmond, Louisiana, where they were commanded by Col. David B. Culberson. They crossed the bayou and charged the enemy at the point of the bayonet, driving them into the timber.
On November 3, 1863, the Eighteenth was in a battle at Bayou Bourbeau, near Grand Coteau, Louisiana. The infantry brigade was formed in a battle line composed of the Fifteenth, Eighteenth and Eleventh Texas infantries. The Fifteenth was commanded by Col. Joseph W. Speight, and they took their position on the right of the brigade. The Eighteenth was commanded by Col. Wilburn H. King and was assigned to the center, while the Eleventh, commanded by Col. Oran Milo Roberts, took their position on the left of the brigade. The battle lasted three hours with twenty-one killed, eighty-two injured, and thirty-eight taken prisoner.
On April 8, 1864, the Eighteenth Texas Infantry engaged in battle at Sabine Cross Roads, near Mansfield, Louisiana. The battle was a stunning victory for the Confederates under the command of Gen. Richard Taylor. This defeat for the Union ultimately caused General Banks to abandon his march toward Shreveport and turn back to New Orleans. The Confederates lost about 1,000 in the battle.
Walker's Texans, including the Eighteenth, engaged General Banks again on April 9, 1864, with an attempt to separate Banks from his gunboat on the Red River, sixteen miles to the east. They fought at Pleasant Hill, Louisiana, with 1,200 casualties for the Confederacy and 1,369 for the Union.
During mid-1864 the Eighteenth Texas Infantry served at Shreveport, Louisiana, and in early 1865 the unit was moved to Hempstead, Texas. Although the regiment is listed among the Confederate Trans-Mississippi forces surrendered at Galveston, it had already ceased to exist by that date. An unofficial report states that the regiment disbanded at Hempstead in late May 1865 when the news of the collapse of the eastern Confederacy reached the region.