What key global event led to the establishment of the United Nations?

The establishment of the United Nations was primarily a response to the devastation and global disruption caused by World War II. It was formed in 1945 with the primary aim of promoting international cooperation, peace, and security to prevent future conflicts on the scale of the Second World War. The catastrophic consequences of the war, including the loss of millions of lives and the destruction of vast areas in Europe and Asia, highlighted the urgent need for a global organization that would facilitate dialogue and cooperation among nations to resolve disputes peacefully. The UN aimed to foster a platform for discussion and conflict resolution, making it a pivotal step in international relations moving forward. The other events listed, while significant in their own right, do not directly correspond to the founding of the United Nations in the same way that World War II does.