OriginHe was an Irish-Canadian, born in Henryville, Montérégie, Québec. The Masterson family moved several times during his childhood, around Quebec, New York, Illinois and finally Kansas. He left the farm as a teenager to become a bufallo hunter. By 1874, he had wandered to Texas. There he took part in an armed conflict between American bufallo hunters and the Comanche. Bat served for a time as a scout for the United States Army, taking part in campaigns against the Comanche and the Kiowa.
Bat was involved in his first gunfight during 1876, in Sweetwater, Texas. (The town was renamed to Mobeetie three years later). He was shot in the pelvis but did manage to kill his opponent. By 1877, Bat moved to Dodge City, Kansas where two of his siblings were working for the local marshal. He was soon hired as well but got in trouble with his boss for his treatment of prisoners. He was jailed himself for a while and had to pay a fine. When allowed to return to law inforcement, Masterson served as a sheriff's deputy. Among his fellow deputies was Wyatt Earp.
Masterson managed to get elected as the sheriff of Ford County, Kansas, staying in office to 1879. He gained some respect for capturing a number of gang members and at least one man wanted for murder. However there was controversy over Bat shooting down Jack Wagner on April 9, 1878. Wagner was a drunken cowboy who had entered Dodge City with his boss Alf Walker. When marshal Ed Masterson, one of Bat's brothers, attempted to disarm the man, Wagner shot him. Ed would die from his bullet wound but Bat was nearby and shot both Wagner and Walker. Wagner died hours later while Walker would enter a long period of recovery. Bat was clearly acting in retaliation and shooting to kill.
Voted out of office, Masterson made his living in the following years as a wandering gambler. On occasion taking part in further gunfights. He seems to have taken a short break from this lifestyle as a marshal in Colorado. He then embraced it again. In 1883, Masterson returned to Dodge City to take part in the so-called "Dodge City War". His old network of political and financial associates of the 1870s had lost ground to that surrounding new mayor Alonzo Webster. Webster was the owner of two local saloons and used his position to drive rivals out of business. Luke Short, a gambler and gunfighter who had recently purchased a saloon in Dodge, had seen the prostitutes employed at his establisment arrested for no particular reason and his business otherwise disrupted. An attempt to protest only led to a gunfight with an overly agressive policeman. The gunfight was bloodless but Webster arranged for Short to be thrown out of town as an undesirable. Short contacted old friends like Bat and Earp to help him out. They also contacted or hired various old frends and acquaintances. Soon a small army of gunfighters, several with considerable reputations, arrived in Dodge. Webster had to negotiate a "peace" between the factions, accepting Short back in town and cease interfering with his business.
Returning to wandering around, Masterson resurfaces by 1889 in Denver, Colorado. He was involved with famed con artist Soapy Smith in a voting fraud case concerning the local elections. A subsequent trial revealed that Smith had ties of corruption to both the mayor and the chief of police. In the context, Masterson was a relatively small fish. He seems to have earned enough money to purchase a local theater and 1891 would see his marriage to actress Emma Walters. The rest of the 1890s involved his continued career in gambling but also some new interests, He promoted prize fights while traveling around, even founding an athletic club focusing on boxing. He also gained his own newspaper column in Denver, dealing with sports in general.
He left the West for New York City c. 1902, succesfully seeking employement in the local press. He kept on gambling though it cost him a few arrests. However his reputation from his Western days helped him befriend politician Theodore Roosevelt. Roosevelt arranged his appointment as deputy marshal of the Southern District of New York in 1908. His duties consisted of keeping the peace in the grand jury room whenever the Federal attorney held court, earning him an annual salary of about 2,000 dollars. . He had considerable free time to keep on writing his newspaper columns. Masterson kept his office until 1912, wnen William Howard Taft contacted a purge of various Roosevelt supporters from government positions. He kept writing his columns until his death in 1921. He died from a heart attack while working on a column.