This document discusses the period known as the Long Nineteenth Century (c. 1885-1915), which represented the zenith of Western Civilization. Known as the Belle Époque, this era ended with the outbreak of World War I in 1914. The war rapidly expanded into a global conflict by 1915 and marked a civilizational shift between the traditionalism of the 19th century and the modernism of the 20th century. The document analyzes the fundamental causes of WWI, arguing it was fought primarily to maintain the aristocratic social and political status quo in Germany, Austria, Russia, and Britain against the rise of populism and socialism.