XX Century History (Summary)

The early arms races of the 20th century escalated into a war which involved many powerful nations: World War I (1914–1918). Technological advancements changed the way war was fought, as new inventions such as machine guns, tanks, chemical weapons, grenades, and military aircraft modified tactics and strategy. After more than four years of trench warfare in western Europe, and 20 million dead, those powers who had formed the Triple Entente (France, Britain, and Russia, later replaced by the United States and joined by Italy) emerged victorious over the Triple Alliance (Germany, Austria-Hungary, and the Ottoman Empire). In addition to annexing much of the colonial possessions of the vanquished states, the Triple Entente exacted punitive restitution payments from their former foes, plunging Germany in particular into economic depression. The Tsarist regime of His Imperial Majesty Nicholas II was overthrown during the conflict and Russia was transitioned into the first ever communist state, and the Austro-Hungarian and Ottoman empires were dismantled at the war's conclusion.

http://en.wikipedia.org/wiki/20th_century