The 20th century opened with Europe at an apex of wealth and power, and with much of the world under its direct colonial control or its indirect domination. Much of the rest of the world was influenced by heavily Europeanized nations: the United States and Japan. As the century unfolded, however, the global system dominated by rival powers was subjected to severe strains, and ultimately seemed to yield to a more fluid structure of independent nations organized on Western models.
This transformation was catalyzed by wars of unparalleled scope and devastation. World War I destroyed many of Europe’s empires and monarchies, and weakened Britain and France. In its aftermath, powerful ideologies arose. The Russian Revolution of 1917 created the first communist state, while the 1920s and 1930s saw militaristic fascist dictatorships gain control in Italy, Germany, Spain and elsewhere.
Ongoing national rivalries, exacerbated by the economic turmoil of the Great Depression, helped precipitate World War II. The militaristic dictatorships of Europe and Japan pursued an ultimately doomed course of imperialist expansionism. Their defeat opened the way for the advance of Socialism and Communism into Central Europe, Yugoslavia, Bulgaria, Romania, Albania, China, North Vietnam and North Korea.
After World War II ended in 1945, the United Nations was founded in the hope of allaying conflicts among nations and preventing future wars. The Soviet Union, the United States, the United Kingdom and China were recognized as the Allied “Big Four” during the war and considered as the primary victors of World War II. With the addition of France, these five countries became the permanent seats in the United Nations Security Council. The war had, however, left two nations, the United States and the Soviet Union, with principal power to guide international affairs. Each was suspicious of the other and feared a global spread of the other’s political-economic model. This led to the Cold War, a forty-five-year stand-off between the United States, the Soviet Union, and their respective allies. With the development of nuclear weapons and the subsequent arms race, all of humanity were put at risk of nuclear war between the two superpowers. Such war being viewed as impractical, proxy wars were instead waged, at the expense of non-nuclear-armed Third World countries.
The Cold War lasted to the 1990s, when the Soviet Union’s communist system began to collapse, unable to compete economically with the United States and western Europe; the Soviets’ Central European”satellites” reasserted their national sovereignty, and in 1991 the Soviet Union itself disintegrated.The United States for the time being was left as the “sole remaining superpower”. After the 1970s, the United States’ superpower status came into question as that country’s economic supremacy began to show signs of slippage.