Why was the league of nations successful?

.....it wasn't. The League of Nations was President Woodrow Wilson's brainchild to avert another international catastrophe in the form of another world war. He said that the "world must be made safe for democracy", but because the U.S. did not join the League, much to Wilson's lament, he claimed that the scourge of war would be visited upon the next generation of the world's citizens. He was correct, and WWII cost the world 50 million lives.