World War I, also known as the Great War, lasted from 1914 to 1918 and involved most of the world's great powers. It was triggered by the assassination of Archduke Franz Ferdinand of Austria-Hungary in 1914, escalating from a regional conflict into a global war. The war was characterized by trench warfare, artillery bombardments, and new technologies such as tanks and chemical weapons. It resulted in millions of casualties and significant social and political upheaval across Europe. World War II began in 1939 with Germany's invasion of Poland and lasted until 1945. It was the deadliest conflict in human history, involving the Axis powers led by Germany, Italy, and Japan against the Allies, including the United States, the Soviet Union, and the United Kingdom. World War II saw widespread use of air power, mechanized warfare, and genocide, including the Holocaust. The war ended with the unconditional surrender of the Axis powers and the establishment of the United Nations to prevent future conflicts. Both wars had profound and far-reaching consequences, reshaping the global political landscape, leading to the rise of new superpowers, and laying the groundwork for the Cold War. They also spurred advancements in technology, medicine, and international cooperation, while leaving a legacy of devastation and trauma that continues to shape the world today.