I believe the main reason why the U.N. was created was to prevent wars by facilitating cooperation between countries.
Explanation:
The United Nations, formerly known as the League of Nations, was established in the 20th century. According to the official website, the U.N's four primary goals are the following: "To keep peace throughout the world; to develop friendly relations among nations; to help nations work together to improve the lives of poor people, to conquer hunger, disease and illiteracy, and to encourage respect for each other’s rights and freedoms; to be a center for harmonizing the actions of nations to achieve these goals." Hope this helps; have a great day!