The major global conflict that involved the Axis powers and the Allies was World War II, which lasted from 1939 to 1945. This devastating conflict arose from unresolved issues from World War I and the rise of totalitarian regimes in Germany, Italy, and Japan. The war saw major battles across Europe, Africa, and the Pacific, with significant events including the Holocaust, the use of atomic bombs, and the D-Day invasion. The Allies, including the United States, the Soviet Union, and the United Kingdom, ultimately defeated the Axis powers. The war profoundly reshaped international relations and led to the establishment of the United Nations.