German Empire
The high command under Paul von Hindenburg and Erich Ludendorff increasingly controlled the country, but in October after the failed offensive in spring 1918, the German armies were in retreat, allies Austria-Hungary and the Ottoman Empire had collapsed, and Bulgaria had surrendered. The Empire collapsed in the November 1918 Revolution with the abdications of its monarchs. This left a postwar federal republic and a devastated and unsatisfied populace, which later led to the rise of Adolf Hitler and Nazism.
Societal collapse
The decline of the Roman Empire is one of the events traditionally marking the end of Classical Antiquity and the beginning of the European Middle Ages. Throughout the 5th century, the Empire's territories in western Europe and northwestern Africa, including Italy, fell to various invading or indigenous peoples in what is sometimes called the Barbarian invasions, although the eastern half still survived with borders essentially intact for another two centuries (until the Arab expansion). This view of the collapse of the Roman Empire is challenged, however, by modern historians who see Rome as merely transforming from the Western Empire into barbarian kingdoms as the Western Emperors delegated themselves out of existence, and the East transforming into the Byzantine Empire, which only fell in 1453 AD.