Variety Hall shootout
Mather had first ventured to Las Vegas as a part of the Dodge City Gang, which also included gunmen John Joshua Webb and "Arkansas" Dave Rudabaugh. Gambler Doc Holliday was also in town at the time, and though generally listed as a member, he was not. However, he was a friend to the gang. The gang was organized by Justice of the Peace Hoodoo Brown, to control the gambling houses in Las Vegas, muscling out any unwanted rivals, thus raking in profits. Dave Mather at that time had a reputation as a gunman, but no real documented accounts of gunfights short of his involvement in the Railroad Wars as a hired gun, with his time in Las Vegas being prior to his well-known 1884 gunfight with lawman Tom Nixon in Dodge City, Kansas.
On January 22, 1880, Marshal Joe Carson entered the Close and Patterson's Variety Hall due to complaints by citizens of some rowdy customers. Whether or not Mather was actually deputized has never been confirmed, but it is believed that he was. The account told most often has him going in with Carson, with some accounts listing him as Carson's deputy, while others simply say they were together that day. Cowboys T.J. House, James West, John Dorsey, and William Randall had been going around town that day, in and out of saloons, generally making trouble. The cowboys were alleged to have thrown their glasses at the bartender, and dared anyone present to stop them.
A "no guns in town limits" rule was in effect, a reason to believe that Mather was in fact deputized, as he was armed. Marshal Carson demanded that the cowboys relinquish their weapons, to which they refused. A shootout between Carson and the cowboys started, with the marshall falling dead. Dave Mather drew his gun and returned fire. When the gunfire died down Mather was still standing. William “Big” Randall was mortally wounded, and James West was too badly injured to escape. The other two men, John Dorsey and also wounded T.J. House, managed to make their way to the stable and escape.
House and Dorsey were captured two weeks later, and brought to the Las Vegas jail to await trial. An angry mob broke into the jail and pulled both House, Dorsey and West from their cell, and lynched them. The gunfight was the first substantiated account to which Mather's name could be attached, and it launched him into western fame as a gunman.