What was the name of the international organization that was in charge of maintaining world peace between world war 1 and world war 2

The League of Nations

Explanation:

This was a peaceful gathering of the major nations of the world from Spain and UK, as well as France and Canada. It was basically the United Nations of the early 20th century, founded in 1920 by Woodrow Wilson President of the United States to help oversee that the world will never again have a war quite like WWI again, that idea failed after 19 years.

might be agreeing to participate ethically with other european nations in the slave trade

or notifying other european nations when taking possession   of african territories

because the vietnam war was fought in an especially brutal and untraditional way