Decline of the Byzantine Empire of Constantinople in 1453. The process by which the empire waned, and from when its decline can be traced, is a matter of scholarly debate. In some cases, the entire history of the Byzantine Empire has been portrayed as a protracted period of decline of the Roman Empire. This holds especially for Enlightenment era writers such as Edward Gibbon, author of "The History of the Decline and Fall of the Roman Empire", published in six volumes between 1776 and 1789, whose view was coloured by pro-western or anti-clerical biases, and tended to see the whole ten-century empire as merely a
Historiography of the fall of the Western Roman Empire catastrophic: Peter Heather, in his "The Fall of the Roman Empire" (2005), maintains the Roman imperial system with its sometimes violent imperial transitions and problematic communications notwithstanding, was in fairly good shape during the first, second, and part of the 3rd centuries AD. According to Heather, the first real indication of trouble was the emergence in Iran of the Sassanid Persian empire (226–651). As reviewed by one writer on Heather's writing, Heather goes on to state—in the tradition of Gibbon and Bury—that it took the Roman Empire about half a century to cope with the Sassanid threat, which it did