Edward Gibbon 
History of The Decline and Fall of The Roman Empire Vol IV 

The History of the Decline and Fall of the Roman Empire[a] is a six-volume work by the English historian Edward Gibbon. It traces Western civilisation (as well as the Islamic and Mongolian conquests) from the height of the Roman Empire to the fall of Byzantium. The work covers the history, from 98 to 1590, of the Roman Empire, the history of early Christianity and then of the Roman State Church, and the history of Europe, and discusses the decline of the Roman Empire in the East and West. (Excerpt from Wikipedia)