The rise of nationalism and militarism: After the First World War, there was a resurgence of nationalism and militarism in many countries. This was due in part to the economic and political instability that followed the war, as well as the revanchist desires of Germany and other defeated powers.
The failure of the League of Nations: The League of Nations was an international organization that was created after the First World War to promote peace and cooperation between nations. However, the League was unable to prevent the outbreak of the Second World War. This was due in part to the fact that the United States did not join the League, and also because the League did not have the power to enforce its decisions.
The appeasement of Nazi Germany: In the 1930s, many countries adopted a policy of appeasement towards Nazi Germany. This was in the hope that Nazi Germany could be satisfied without war. However, this policy failed, and it ultimately led to the outbreak of the Second World War.
In conclusion, the peace movement failed between the first and second world wars because of a number of factors, including the rise of nationalism and militarism, the failure of the League of Nations, and the appeasement of Nazi Germany.