The war caused the disintegration of four empires: the Austro-Hungarian, German, Ottoman, and Russian. Germany lost its overseas empire, and states such as Czechoslovakiaand Yugoslavia were created, or recreated, as in the cases of Lithuania and Poland. This contributed to a decisive break with the world order that had emerged after the Napoleonic Wars, which was modified by the mid-19th century's nationalistic revolutions. The results of World War I would also be important factors in the development of World War II just over two decades later.
Much of the fighting in World War I took place along the Western Front, within a system of opposing manned trenches and fortifications (separated by a "no man's land") running from the North Sea to the border of Switzerland. On the Eastern Front, the vast eastern plains and limited rail network prevented a trench warfare stalemate from developing, although the scale of the conflict was just as large. Hostilities also occurred on and under the sea and - for the first time - in the air.
KILLING FIELDS OF WORLD WAR I, by Cotter Bass, provides a brief but graphic overview of the battlefield horrors of World War I.