The Byzantine Empire was one of the longest surviving empires the world has ever seen an empire whose importance for Western civilization is still not fully acknowledged. This book explains how Byzantium functioned as Europe's most impor-tant bulwark against Islam for almost 1000 years and it also explains why there would be no Western culture in Europe and in the Americas if Byzantium had fallen to the Muslims in the seventh or eighth century that is during the reign of the Emperors Heraclius and Constantine IV and not in 1453.Furthermore it reveals striking parallels between this medi- eval state and today's Western powers particularly the USA and the European Union and analyzes the reasons which finally led to Byzantium's demise. The book also exhorts the West to learn from the mistakes which were made in Byzantium in situations of crisis and which by comparison were similar to the crises the Western world is experiencing today.