Winston Churchill's major achievements in the 20th century include his leadership as Prime Minister during World War II, where he rallied the British people with his powerful oratory. His steadfast resolve helped prevent Nazi expansion in Europe. He also played a critical role in forging alliances with the United States and Soviet Union, facilitating the defeat of the Axis powers. Post-war, Churchill promoted the idea of a United Europe to ensure peace. Additionally, he received the Nobel Prize in Literature in 1953, recognizing his significant contributions to writing and history.