* The collapse of the Russian Empire. The Russian Empire entered World War I as one of the most powerful countries in the world. However, the war quickly proved to be a disaster for Russia. The country suffered massive casualties, and the economy was in ruins. In 1917, the Russian Revolution broke out, and the Romanov dynasty was overthrown. The new Soviet government made peace with Germany, and Russia withdrew from the war.
* The United States emerged as a global superpower. The United States entered World War I in 1917, and its involvement helped to turn the tide of the war in favor of the Allies. After the war, the United States became the world's leading creditor nation, and its economy was booming. The United States also played a major role in the establishment of the League of Nations, an international organization that was designed to prevent future wars.
* The decline of the British Empire. The British Empire was one of the most powerful empires in the world before World War I. However, the war took a heavy toll on the British Empire. The country lost millions of soldiers, and the economy was severely damaged. After the war, the British Empire began to decline, and many of its colonies gained independence.
World War 2
* The rise of the United States as a global superpower. The United States entered World War II in 1941, and its involvement helped to turn the tide of the war in favor of the Allies. After the war, the United States became the world's leading superpower. The United States had the most powerful economy in the world, and it also had a monopoly on nuclear weapons.
* The decline of the British Empire. The British Empire was further weakened by World War II. The country suffered even more losses than it did in World War I, and the economy was in even worse shape. After the war, the British Empire continued to decline, and many more of its colonies gained independence.
* The rise of the Soviet Union as a global superpower. The Soviet Union emerged from World War II as a major global power. The country had a powerful military, and it also had a large and rapidly growing economy. The Soviet Union and the United States became rivals in the Cold War, a global conflict that lasted for decades.
* The decolonization of Africa and Asia. World War II also led to the decolonization of Africa and Asia. Many of the European countries that had colonized Africa and Asia were weakened by the war, and they were no longer able to maintain their empires. As a result, many African and Asian countries gained independence after the war.