1819: Allan Pinkerton, founder of Pinkerton's National Detective Agency, was born in Glasgow, Scotland. Pinkerton emigrated to the United States in 1842. He was an ardent abolitionist, and his barrel shop functioned as a "station" for escaped slaves traveling the Underground Railroad to freedom in the North. Pinkerton's career as a detective began by chance when he discovered a gang of counterfeiters operating in an area where he was gathering wood. His assistance - first in arresting these men and then another counterfeiter, led to his appointment as deputy sheriff of Kane County, Illinois, and, later, as Chicago's first full-time detective. Pinkerton left his job with the Chicago police force to start his own detective agency. In 1861, while investigating a railway case, Pinkerton uncovered an apparent assassination plot against Abraham Lincoln. It was believed that conspirators intended to kill Lincoln in Baltimore during a stop along the way to his inauguration. Pinkerton warned Lincoln of the threat, and the president-elect's itinerary was changed so that he passed through the city secretly at night. (Source: Library of Congress)