For many year, they were faced each other from trenchers dug in the ground. Within a week, Russia, Belgium, France, Great Britain and Serbia had lined up against Austria -Hungary and Germany, and World War I had begun. In this war, were used for the first time: trucks, largecaliber cannons, hot air balloons and airplanes. According to an aggressive military strategy known as the Schlieffen Plan, Germany began fighting World War I on two fronts, invading France through neutral Belgium in the west and confronting Russia in the east.
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