What was established in 1920 to promote international cooperation and peace?

The League of Nations was established in 1920 following World War I with the primary goal of promoting international cooperation and peace. Its creation was a response to the devastation of the war, aiming to provide a platform for resolving disputes between countries through dialogue rather than conflict. The League established guidelines and standards for international relations, promoting disarmament and addressing issues such as labor rights and humanitarian concerns.

The League of Nations is significant not only because it was the first worldwide organization dedicated to maintaining peace, but also because it laid the groundwork for the establishment of the United Nations after World War II, which built upon the League's principles and aimed for a stronger framework for global governance. While the other options listed, such as the United Nations, World Trade Organization, and the European Union, are vital to international relations, they were founded at later dates and served different functions within global political and economic systems.