Shotgun messenger

A circa 1904 drawing of an Overland Mail stagecoach under attack—note guard with shotgun sitting to the left of the driver

In the late 19th and early 20th centuries, a shotgun messenger was a private "express messenger" and guard, especially on a stagecoach but also on a train, in charge of overseeing and guarding a valuable private shipment, such as particularly the contents of a strongbox (on a stagecoach) or safe (on a train).