Lecture Notes





































History of Collective Security

This cartoon blames the United States for the failure of the League of Nations.

During World War I, U.S. President Woodrow Wilson came up with a 14-Point Plan for ending the war and achieving a lasting peace. His last point was a “League of Nations” that would, in theory, maintain peace through collective security. The idea of collective security was not entirely new, but this would be the first time that it would be tried on a global scale.

Unfortunately, the League of Nations was a failure. As Germany, Italy, and Japan invaded their neighbors in the 1930s, the League of Nations proved powerless—or unwilling—to stop them. That’s one problem with collective security: Although countries are pledged to defend each other, many countries will refuse to do so, if such an act is not in their own best interest or is thought to be too risky or expensive.  The result was World War II, the bloodiest war in world history.

Another problem with the League of Nations is that the U.S. never joined. Following the war, the U.S. retreated into an isolationist mood; Americans were wary of “entangling alliances” which might commit the U.S. to more foreign wars. So Congress refused to ratify the treaty which created the League of Nations—even though the whole thing had been President Wilson’s idea.

The failure of the U.S. to join the League of Nations is often cited as the primary reason the League of Nations was such a spectacular failure. 

A Second Try

The U.N. was formed immediately following World War II. It was based on previous agreements such as the League of Nations and the Atlantic Charter. The United Nations represents a “second try” at the idea of collective security.

The United Nations, like the League of Nations before it, is a collective security agreement. If any state attacks another state, all the members of the United Nations are supposed to come to the defense of the country that has been attacked.

Has collective security worked better this second time around? Not really. Although the UN does a lot of good work, it has not proven particularly successful at preventing wars. True, we have managed to avoid World War III—but that’s not saying much. There have been many regional wars since the United Nations was formed in 1945. The idea of collective security just doesn’t seem to work so well in the real world.


Check Your Understanding

  1. Why didn't the United States join the League of Nations? 
  2. Why did the League of Nations fail to prevent World War II?
  3. Has the United Nations been more successful at preventing wars than the League of Nations? Explain your answer.