U.S. troops from Fort Bridger imposed martial law until the track-layers had passed. Bear River City soon became another railroad ghost town.

From Wyoming, Smith moved on to Kit Carson, Colorado, where he held a similar position before making his way to Abilene, Kansas. In June, he was appointed the Kansas Cowtown's first marshal, which badly was in need of law enforcement. He was paid a salary of $150 a month plus 2$ for each conviction of persons arrested. One of Smith’s first official acts was to ban all weapons in town without a permit. Within 48 hours,  everyone had turned over their weapons to Smith, but he had had to knock down two thugs before they surrendered their weapons.

Known as "No gun marshal," he gained a reputation for subduing assailants with his fists rather than a gun, and where lawlessness reigned supreme, he was forced to often use them. The decision to ban guns was unpopular with some members of the community and during the next few months he survived two assassination attempts.

On November 2, 1870, Smith was sent to a small settle some ten miles from Abilene to arrest a man named Andrew McConnell, who was charged with murdering John Shea, a local farmer. However, when he arrived at McConnell’s home, telling him that he had a warrant for his arrest, McConnell shot Smith in the chest. Smith returned fire wounding McConnell before falling to the ground. McConnell's co-conspirator in the original crime, a man named Moses Miles, then struck Smith with his gun, grabbed an axe and nearly chopped Smith's head from his body. Thomas "Bear River” Smith was buried in the Abilene Cemetery, where his body remains today.

The murdering pair of McConnell and Miles were soon captured and in March, 1871, both men were found guilty of murder and were sentenced to long terms in prison for their gruesome crime.

Afterwards, the town of Abilene returned to its lawless ways until the next marshal could be hired – that of James Butler "Wild Bill" Hickok in April, 1871.