Allan Pinkerton was one of the most influential people that shaped law enforcement in America. Among other exploits, he prevented an assassination attempt on Abraham Lincoln; organized the first official Secret Service for duty behind Confederate lines during the Civil War and rode with lawmen along the Old Frontier, hunting down members of Jesse James' gang, the Reno brothers and other outlaws.
Pinkerton was well known to the members of the 19th Century underworld. They knew he was incorruptible and so was his agency. They were also well acquainted with Pinkerton's tenacity, exemplified by the firm's motto "We never sleep". If necessary he and his agents would chase lawbreakers to the ends of the earth.
Pinkerton was born in Glasgow, Scotland, in 1819, the son of a policeman. Shortly after his marriage in 1842, the Pinkerton's emigrated to North America, eventually selecting Chicago as home.