The origins of today's Texas Ranger Division trace back to the first days of Anglo-American settlement of what is today the State of Texas, when it was part of the Province of Coahuila y Tejas belonging to the newly independent country of Mexico. The unique characteristics that the Rangers adopted during the force's formative years and that give the division its heritage today—characteristics for which the Texas Rangers would become world-renowned—have been accounted for by the nature of the Rangers' duties, which was to protect a thinly populated frontier against protracted hostilities, first with Plains Natives tribes, and after the Texas Revolution, hostilities with Mexico.
Texas historian T.R. Fehrenbach explains the Rangers' uniqueness:
The Rangers were to be described many times, at first as state troops, later as a police force or constabulary. During most of the 19th century, they were neither. They were apart from the regular army, the militia or national guard, and were never a true police force. They were instead one of the most colorful, efficient, and deadly band of irregular partisans on the side of law and order the world has seen. They were called into being by the needs of a war frontier, by a society that could not afford a regular army. Texans passed in and out of the Rangers regularly; in the early years, a very high proportion of all west Texans served from time to time. If they bore certain similarities to Mamelukes and Cossacks, they were never quite the same.
By the early 1830s, the Mexican War of Independence had subsided, and some 60 to 70 families had settled in Texas—most of them from the United States. Because there was no regular army to protect the citizens against attacks by native tribes and bandits, in 1823, Stephen F. Austin organized small, informal armed groups whose duties required them to range over the countryside, and who thus came to be known as "rangers". Around August 4, 1823, Austin wrote that he would " ... employ ten men ... to act as rangers for the common defense ... the wages I will give said ten men is fifteen dollars a month payable in property ... " John Jackson Tumlinson Sr., the first alcalde of the Colorado district, is considered by many historians of the Texas Rangers to be the first killed in the line of duty. While there is some discussion as to when Austin actually employed men as "rangers", Texas Ranger lore dates the anniversary year of their organization to this event.
However, the Texas Rangers were not formally constituted until 1835. Austin returned to Texas after having been imprisoned in Mexico City and helped organize a council to govern the group. On October 17, at a consultation of the Provisional Government of Texas, Daniel Parker proposed a resolution to establish the Texas Rangers. He proposed creating three companies that would total some 60 men and would be known by "uniforms" consisting of a light duster and an identification badge made from a Mexican peso. They were instituted by Texan lawmakers on November 24. On November 28, 1835, Robert McAlpin Williamson was chosen to be the first Major of the Texas Rangers. Within two years the Rangers grew to more than 300 men.
In their early days, Rangers performed tasks of protecting the Texas frontier against Native Americans’ attacks on the settlers. During the Texas Revolution, they served mainly as scouts, spies, couriers, and guides for the settlers fleeing before the Mexican Army and performed rear guard during the Runaway Scrape and general support duties. These minor roles continued after independence, when the region became the Republic of Texas under President Sam Houston. Houston, who had lived with the Cherokee for many years (and who had taken a Cherokee wife), favored peaceful coexistence with Natives, a policy that left little space for a force with the Rangers' characteristics.
This situation changed radically when Mirabeau B. Lamar became president of the Republic of Texas in December 1838. Lamar had participated in skirmishes with the Cherokee in his home state of Georgia; like most Texians, he had not forgotten the support the Cherokee had given the Mexicans in the Córdova Rebellion against the Republic. He favored the eradication of Native Americans in Texas—a view that he shared with Chief Justice of the Supreme Court Thomas Rusk. Lamar saw in the Rangers the perfect tool for the task, and he obtained permission from the Texas Legislature to raise a force of 56 Rangers, along with other volunteer companies. During the following three years, he engaged the Rangers in a war against the Cherokee and the Comanche and succeeded in weakening their territorial control.
Sam Houston was re-elected President of Texas on December 12, 1841. He had taken note of the Rangers' cost-efficiency and increased their number to 150. Under Captain John Coffee "Jack" Hays' leadership, the force played an important role in the defense against the Mexican invasion led by General Adrian Woll in 1842 and against attacks by Natives. The First Regiment of Texas Mounted Rifle Volunteers was also known as "Hays' Texas Rangers". Despite his youth at the time, the charismatic Hays was a rallying figure to his men and is often considered responsible for giving cohesion, discipline and a group mentality to the Rangers. Flacco, a chief of the allied Native tribe of the Lipan, used to call Hays Bravo too much. The adoption of the state-of-the-art five-shot Colt Paterson revolver (which had been turned down by the U.S. Army) was also his work. Hays trained his men to aim, fire and reload their weapons from horseback, a radical innovation from the usual contemporary technique of dismounting before shooting at enemies and reloading, which was a necessity with more cumbersome weaponry. This tactic was put to devastating effect, and it was imitated shortly afterwards by the military, Texian and American. At the suggestion of one of Hays's officers, Samuel Hamilton Walker, these revolvers soon evolved into the famous, enhanced six-shot version, the Walker Colt; 1,000 of these revolvers were issued to the United States Mounted Rifles engaged in the Mexican–American War. During these years, famous Rangers such as Hays, Walker, Benjamin McCulloch and William "Bigfoot" Wallace first established their reputation as frontier fighters.
With the annexation of Texas within the United States and the Mexican–American War in 1846, several companies of Rangers were mustered into federal service and proved themselves at the battles of Palo Alto and Resaca de la Palma. From that moment on, their effectiveness as guerrilla fighters and guides to the federal army through a territory that they were familiar with marked the pace of the American offensive. Rangers played an important role in the battles of Monterrey and Buena Vista. The army, commanded by General Winfield Scott, landed at Veracruz in March 1847, and the Rangers once again provided valuable support at the ensuing Siege of Veracruz and the battles of Cerro Gordo and Chapultepec. They were also responsible for the defeat of the fierce Mexican guerrilleros that hindered the advance of the federal troops, which they achieved ruthlessly and efficiently. By then, the Rangers had earned themselves a considerable reputation that approached the legendary among Mexicans, and when Ranger companies entered and occupied Mexico City with the U.S. Army in September 1847, los Diablos Tejanos (the "Texas Devils") were received with reverence and fear. Their role in the Mexican–American War also won them nationwide fame in the United States, and news of their exploits in the contemporary press became common, effectively establishing the Rangers as part of American folklore. As the Victoria Advocate reported in the November 16, 1848, issue:
Four newly raised ranging companies, have all been organized, and taken their several stations on our frontier. We are much pleased. We know they are true men, and they know exactly what they are about. With many of them, Native and Mexican fighting has been their trade for years. That they may be permanently retained in the service on our frontier is extremely desirable, and we cannot permit ourselves to doubt such will be the case.