Thomas O'Folliard was born in 1858 to Irish immigrant parents. When he was a boy, both of his parents died of smallpox, and he was raised by relatives in Uvalde, Texas.
He began his life of crime by taking part in horse theft with Emil Fritz. Fritz later became a gunman in the Lincoln County War in New Mexico.
Through Fritz's influence, O'Folliard traveled to New Mexico. There he met the infamous Billy the Kid, and together with Fritz they allied with Alexander McSween's side in the Lincoln County War.
During the conflict, O'Folliard was hit in the shoulder by a bullet. The wound came on February 18, 1878.
That same day, a group of law enforcement officers arrested John Tunstall as he was accompanied by ranchers Richard "Dick" Brewer, Billy the Kid, John Middleton, Henry Newton Brown, Robert A. Widenmann, and Fred Waite. They were in the process of driving Tunstall's nine remaining horses back to Lincoln.
Later investigations by Frank Warner Angel, the home secretary's special investigator, confirmed that Tunstall was mercilessly shot dead by Jesse Evans, William Morton, and Tom Hill. Tunstall's murder was witnessed from afar by several members of his party, including Richard Brewer and Billy the Kid.
This tragic event marked the beginning of the infamous Lincoln County War. To avenge Tunstall's murder, his cowhands and other local citizens formed a collective known as The Regulators.
They were motivated by a desire for justice in a system where territorial criminal justice was heavily influenced by allies of Murphy and Dolan. While The Regulators at various times included dozens of American and Mexican cowboys, a core group of about a dozen main members was known as the Ironclad.
Among them were figures such as McArdy, Richard "Dick" Brewer, Frank McNab, Doc Scurlock, Jim French, John Middleton, George Coe, Frank Coe, Jose Chavez y Chavez, Charlie Bowdre, Tom O'Folliard, Fred Waite, and Henry Newton Brown.
The Regulators took action against members of the sheriff's team responsible for Tunstall's murder. Following an appointment by the Lincoln County Justice of the Peace, the agency, along with Constable Martinez, worked to enforce lawful arrest warrants for Tunstall's killers.
However, Sheriff Brady intervened and arrested Martinez and his deputies, disregarding their legal authority. Though they were later released, they were determined to bring Tunstall's killers to justice.
They encountered Buck Morton, Dick Lloyd, and Frank Baker near Rio Peñasco. An intense five-mile gunfight ensued between Buck Morton and the pursuers.
In the end, Morton surrendered along with his partner Frank Baker, who was not directly involved in Tunstall's murder but happened to be with Morton and Lloyd. The purpose of the pursuit group was to return the captives to Lincoln unharmed.
The Regulators' captain, Dick Brewer, assured them they would be taken to Lincoln, but the other Regulators insisted on killing the prisoners. One member, William McCloskey, a friend of Morton's, spoke out against the move.
On the afternoon of July 15, 1878, an important clash took place between two opposing forces in Lincoln. The Regulators were besieged at two separate locations: the McSween house and the Ellis store.
On one side were cowboys affiliated with Dolan, Murphy, and Seven Rivers. Inside Ellis's store were individuals such as Scurlock, Bowdre, Middleton, Frank Coe, and several others.
In addition, about 20 members of the Mexican Regulators led by Jose Chavez y Chavez were strategically located throughout town. In the McSween home were notable figures including Alex McSween, his wife Susan, Billy the Kid, Henry Brown, Jim French, Tom O'Folliard, Jose Chavez y Chavez, George Coe, and more than a dozen Mexican Regulators.
This position was the stronghold for their resistance against the opposition. Over the course of the next three days, the men engaged in a fierce gun battle and shouted at each other.
Tragically, Tom Cullins, one of McSween's defenders, fell victim to a stray bullet. At about the same time, Henry Brown, George Coe, and Joe Smith decided to leave the McSween house safely.
They ventured to the Tunstall store, where they chased two Dolan men into an outbuilding with rifles and forced them to plunge to the bottom to escape. The stalemate lasted until the arrival of Colonel Nathan Dudley, the leader of the United States Army forces, with cannons aimed at Ellis's shop and other key positions.
The Army forced Doc Scurlock and his men to abandon their defensive posts. Similarly, the cowboys associated with Chavez withdrew, leaving the rest of the McSween house to face their precarious fate.
On the afternoon of July 19, the Murphy-Dolan faction set fire to the McSween house. As the fire spread rapidly and night fell, Susan McSween, another woman, and five children were allowed out of the house for their safety.
Inside, the remaining men bravely continued to fight the fire. By 9:00 p.m. the situation had worsened, forcing the rest of them to recklessly rush toward the back door of the burning house.
Billy the Kid and Jim French meticulously assessed their predicament, strategizing an escape plan that involved the use of pistols for defense. With Jim French in the lead, followed closely by Billy the Kid, O'Folliard, Jose Chavez y Chavez, and their men risked their lives to escape.
The Dolan men saw them run away and began shooting, tragically taking the life of Harvey Morris, McSween's law partner. In the ensuing chaos, several soldiers entered the backyard with the intention of capturing the rest.
A chaotic gunfight broke out, resulting in the casualties of Alexander McSween and Seven Rivers cowboy Bob Beckwith. Three other Mexican Regulators, confused by the chaos, left in a hurry to meet with Ironclad members not far away.
The Lincoln County War served no purpose other than to foster distrust and hostility in the region. After the feud ended, Thomas spent the next two years with Billy the Kid, engaged in cattle drive efforts across the southwestern lands.
As they attracted more outlaws into their operations, the group became known as Billy the Kid's gang, of which O'Folliard was second in command. However, the gang and its members would soon face dire consequences, being relentlessly pursued by Sheriff Pat Garrett.
Despite their escape attempts, their luck ended on December 19, 1880, when they reached Fort Sumner, New Mexico. There, Pat Garrett and another lawman named Lon Chambers planned ahead, waiting for them.
When O'Folliard and the party arrived, Garrett suddenly appeared and ordered them to stop. Instead, O'Folliard sought to retrieve a firearm but was met with a gunshot to the chest.
Faced with the situation, Billy the Kid and the rest of the group, including Tom Pickett, hurriedly retreated from town. Thomas tried to follow them, but weakened by his wounds he lay back, speaking to his pursuers and begging, "Don't shoot, Garrett, I'm done."
He then begged the sheriff to end his suffering, but Garrett refused. About an hour after being shot, Thomas succumbed to his injuries and died.
He is buried at the Old Fort Sumner Cemetery along with his companions Billy the Kid and Charlie Bowdre. It is worth noting that Thomas was only 22 years old when he met his untimely death.