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. More than nine million soldiers died on the various battlefields, and millions more civilians perished.
The war caused the disintegration of four empires: the Austro-Hungarian, German, Ottoman, and Russian. Germany lost its overseas empire, and states such as Czechoslovakia and 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.
"It must be a peace without victory...Victory would mean peace forced upon the loser, a victor's terms imposed upon the vanquished. It would be accepted in humiliation, under duress, at an intolerable sacrifice, and would leave a sting, a resentment, a bitter memory upon which terms of peace would rest, not permanently, but only as upon quicksand. Only a peace between equals can last."
Helmuth Johann Ludwig von Moltke (May 25, 1848–June 18, 1916), also known as Moltke the Younger, was a nephew of Field MarshalCount Moltke and served as the Chief of the German General Staff from 1906 to 1914. His role in the development of German war plans and the instigation of the First World War is extremely controversial. As Chief of the General Staff Moltke was responsible for the development and execution of the strategic plans of the German Army. There is considerable debate over the nature of his plans. Critics from the so-called "Schlieffen School" argue that Moltke took his predecessor's plan (the "Schlieffen Plan"), modified it without understanding it, and failed to execute it properly during the First World War, thus dooming German efforts.