Hendrick Arnold, guide and spy during the Texas Revolution, emigrated from Mississippi with his parents, Daniel Arnold, apparently a white man, and Rachel Arnold, who was apparently black, in the winter of 1826. The family settled in Stephen F. Austin's colony on the Brazos river. Hendrick is referred to as a Negro, although his brother Holly was regarded as white; both were apparently considered free, although there is no evidence that they were ever formally freed by their father. In July or August of 1827 Hendrick and an Arnold slave named Dolly had a daughter, Harriet. Hendrick held Harriet as a slave.
By the fall of 1835 Arnold had settled in San Antonio and married a woman named Martina (María), a stepdaughter of Erastus (Deaf) Smith. Arnold had a second daughter, Juanita, who may have been Martina's child. While Arnold and Smith were hunting buffalo in the Little River country north of the site of present Austin, Mexican forces under Gen. Martín Perfecto de Cos occupied San Antonio. On their trip home Arnold and Smith came upon Stephen F. Austin's encampment at Salado Creek. Arnold, and soon thereafter Smith, who considered remaining neutral because of his Mexican wife, offered their services as guides to the Texans. In October Arnold took part in the battle of Concepción.
When Edward Burleson, who had replaced Austin as commander, called a council of officers on December 3, 1835, the council decided to postpone an attack on San Antonio, explaining that Arnold was absent and that the officers of one of the divisions refused to march without him. Arnold's whereabouts during his absence are now unknown. When he returned, Benjamin R. Milam called for an attack, which was subsequently called the siege of Bexar. Arnold served as the guide for Milam's division. Francis W. Johnson, leader of the other division, wrote the official report of the battle for himself and Milam, who was killed during the siege. Johnson acknowledged the bravery of all the Texan forces and cited Arnold specifically for his "important service."
On January 3, 1836, Arnold arrived in San Felipe de Austin with his family and that of Erastus Smith. On January 4 he successfully petitioned the General Council of the provisional government of Texas for relief for their families and noted Smith's service for Texas and his wounds suffered in battle. Arnold continued to support the revolution and served in Smith's spy company in the battle of San Jacinto.
After the revolution Arnold was compensated for his service with land a few miles northwest of the site of present Bandera, a relatively unexplored area. Arnold secured adjacent land for his grandmother Catherine Arnold, his father Daniel, and his brother Holly. Holly appears to have been the only family member to settle on the land. Hendrick Arnold lived on the Medina River and operated a gristmill in San Antonio. A portion of the mill was still standing in 1990 near Mission San Juan.
In 1846 Arnold arranged an indentured-servant contract between his daughter Harriet and James Newcomb. Newcomb agreed to pay $750 for her services and then free her after five years. Both Arnold and Newcomb died of cholera before the expiration of the contract. Newcomb's administrator, George M. Martin, petitioned the Texas House of Representatives to permit Harriet to remain in the state as a free woman of color on December 29, 1849. The resolution passed the House; however, Arnold's family made several attempts to regain Harriet from Martin. Martina Arnold took the matter to court, sued Martin for $2,000 plus the $750 due on the indentured-servant contract, and requested that Harriet be returned to her. The final outcome of the case was cloudy; however, it appears that Harriet was allowed to remain in the state as a free woman. Hendrick Arnold died in the cholera epidemic in Bexar County in 1849 and was buried on the banks of the Medina River.