Who is Allan Pinkerton from Flashman & the Angel of the Lord: From the Flashman Papers, 1858-59 and what is their importance? "Flashman_&_the_Angel_of_the_Lord:_From_the_Flashman_Papers

A historical character, Pinkerton is a Scottish born detective, destined to become the most famous in America and to found the U.S. Secret Service during the Civil War. He is on the cusp of fame in 1859. Pinkerton meets narrator Sir Harry Flashman when Annette Mandeville, the wife of Atropos, leader of the pro-slavery Kuklos organization, tries to shake off Kuklos spies in New York City. They are ambushed by Pinkerton's joint police/federal agent task force, a member of which is Annettte.