The History of the Decline and Fall of the Roman Empire, by Edward Gibbon
Chapter V: Sale Of The Empire To Didius Julianus
Public Sale Of The Empire To Didius Julianus By The Prætorian Guards—Clodius Albinus In Britain, Pescennius Niger In Syria, And Septimius Severus In Pannonia, Declare Against The Murderers Of Pertinax—Civil Wars And Victory Of Severus Over His Three Rivals—Relaxation Of Discipline—New Maxims Of Government.