Henry Newton Brown was born in 1857 near Rolla, Missouri. Orphaned at a young age, he was raised by his uncle Jasper and aunt Aldamira Richardson. At 17, he ventured westward, working as a cowboy in Colorado and Texas.

In Texas, Brown allegedly killed a man in a gunfight, prompting him to flee to New Mexico. There, he became involved in the Lincoln County War, aligning with Billy the Kid and the Regulators, a group formed to avenge the murder of rancher John Tunstall.

After the war, Brown drifted through various roles, including a stint as a deputy sheriff in Texas. His aggressive behavior led to his dismissal, and he eventually settled in Caldwell, Kansas. In 1882, he was appointed city marshal, earning a reputation for his strict law enforcement and was even presented with an engraved Winchester rifle by grateful citizens.​

Despite his respected position, Brown struggled financially. In April 1884, he, along with his deputy Ben Wheeler and two associates, planned to rob the Medicine Valley Bank in Medicine Lodge, Kansas. On April 30, they entered the bank, and during the attempted robbery, bank president Wylie Payne and cashier George Geppert were shot and killed.

The gang fled but was quickly pursued by a posse and captured after a brief standoff. They were taken to the local jail, but that evening, a lynch mob stormed the facility. Brown attempted to escape but was shot and killed during the attempt. His accomplices were hanged by the mob.