One of the most famous examples of a peace-keeping body that failed to stop war is the League of Nations. Founded after the Paris Peace Conference in 1919, it eventually proved incapable of halting Axis aggression shortly before the start of World War II.
Key goals for the League of Nations included global disarmament, settling disputes between countries through negotiation and improving global welfare. However, when the League was developed, three of the most powerful countries in the world refused or were not allowed to join. This left the majority of responsibility on Britain and France, who were already weakened due to World War I. This gave the League few options when a country ignored its warnings and little chance of enforcing its decisions.