The First Texas Cavalry, Arizona Brigade, at one time called the Thirty-first Texas Cavalry, had a long and unusual history. The idea for the regiment came from "ex-officio" Confederate governor of Arizona John Robert Baylor in the fall of 1861. Baylor wanted to raise his own Texas brigade that would fight to officially establish Arizona as Confederate territory. Most of the men he initially recruited came from his own regiment, the Second Regiment of Texas Mounted Rifles. Others came from Dallas County and the surrounding area. To establish a presence in Arizona, Baylor planned to attach this new brigade to the New Mexico campaign (see SIBLEY CAMPAIGN), led by Brig. Gen. Henry Hopkins Sibley, in an attempt to establish a Confederate empire in the American Southwest and eventually into Mexico.
Initially Baylor raised a four-company battalion commanded by Lt. Col. Philemon Herbert. After the New Mexico campaign, more companies were added to make the battalion a full regiment, the First Texas Cavalry, Arizona Brigade. Baylor's hope of ever commanding the regiment disappeared after Sibley permanently removed the governor from control of the regiment by promoting the senior Capt. Peter Hardeman, of the Second Regiment of Texas Mounted Rifles, to lieutenant colonel in command. Sibley failed in his attempt to occupy New Mexico, and his entire force retreated to Texas before the First Texas Cavalry, Arizona Brigade filled their ranks. After several months the brigade never reached full strength, ending Baylor's dream of Arizona becoming Confederate controlled territory and the First Texas Cavalry, Arizona Brigade's opportunity to fight in Arizona and New Mexico.
During the summer of 1862, the thirty-one-year-old Peter Hardeman became ill. While he recovered from his sickness, his cousin William P. "Gotch" Hardeman, a veteran of the New Mexico Campaign, took temporary command of the battalion encamped at Victoria, Texas. During his brief period as commander of the battalion William reorganized it and increased the battalion to six companies by adding unattached cavalry companies commanded by Capt. W. G. Welch and Capt. Joseph Head, Company F and Company H, respectively. While the companies camped at Victoria, they recruited men from nearby Goliad County, which produced one more company and increased the battalion to a regiment with eight full companies. After Peter recovered, William left to continue his military service in Louisiana with the Fourth Texas Cavalry. The regiment remained in Victoria until April 1863 when Hardeman received orders that his command would be attached to the newly-formed Bankhead's brigade, later called Gano's Brigade, camped at Fort Hood near San Antonio. While camped at Fort Hood, Hardeman acquired more men from Bexar and Comal counties to increase his strength further.
While part of Gano's Brigade, Hardeman disbanded company F and transferred the enlisted men to the Seventeenth Texas Field Battery. Additionally the regiment served alongside Confederate Indians in Arkansas where they experienced limited fighting in the Red River campaign at Poison Spring and the Indian Territory in the Second Battle of Cabin Creek. After returning to Texas from Cabin Creek the regiment received orders to move to Hempstead, Texas, where they dismounted. After a brief stay at Hempstead, the First Texas Cavalry, Arizona Brigade, moved to Houston and Harrisburg on the Texas coast. Due to the disbandment of Company F, being dismounted, and a large number of men that deserted, the regiment's strength dwindled to only 175 men when it disbanded on May 15 at a camp on Sims Bayou, near Richmond on the Brazos River. Shortly after disbanding in May 1865, Hardeman left Texas with his family for Brazil where they lived on a plantation. Hardeman died in 1882 in Cillo, Brazil, where his family buried him.