How strong was the League of Nations?

The League of Nations was created from the Treaty of Versailles after WWI. However, unfortunately no countries were willing to create the League of Nations. They joined and created the League because Wilson, the president of one the strongest countries U.S, said he wanted to create a better world. So, the countries in the League seemed lacking of eagerness. How effective was the League of Nations, then? It was true that the League of …

…between Bolivia and Paraguay. The League of Nations indeed had good effect and improved the world a lot. They stopped several wars and saved many POWs, slaves, refugees, sick people, etc. However, their failures were bigger then their successes. Besides the two crises I mentioned above, there were numerous conflicts that the League couldn't stop. In conclusion, the League of Nations affected the world in some aspect, but taken altogether, it didn't help the world.