1) The sheer size of the conflict: World War 2 was the largest and deadliest war in human history, involving over 100 million people from more than 30 countries. The war was fought in multiple theaters, including Europe, North Africa, the Middle East, Asia, and the Pacific, making it difficult for any one side to gain a decisive advantage.
2) The development of new technologies: World War 2 saw the introduction of new military technologies, such as the atomic bomb, long-range bombers, and radar, which changed the nature of warfare and made it more difficult to end.
3) The rise of nationalism and fascism: The war was fueled by the rise of nationalism and fascism in Europe and Asia, which made it difficult for countries to compromise and reach a peace agreement.
4) The failure of the League of Nations: The League of Nations was an international organization that was established after World War 1 to prevent future conflicts, but it was unable to prevent the outbreak of World War 2.
5) The Holocaust: The Holocaust, in which the Nazi regime killed six million European Jews, was one of the most horrific atrocities in human history. It further complicated efforts to end the war and contributed to the deep-seated hatred between the Nazis and the Allies.
6) The complex political landscape: World War 2 involved a complex web of alliances and rivalries between countries, making it difficult to negotiate a peace agreement that would satisfy all sides.
7) The stubbornness of the combatants: The leaders of the Axis and Allied powers were determined to achieve their goals, even at the cost of millions of lives. This made it difficult to find a compromise that would end the war.