The Treaty of Versailles, which came out of the Paris Peace Conference in 1919, was very punitive towards Germany. Germany was forced to admit responsibility for causing the Great War (World War I). We now call that "the war guilt" clause of the treaty. Germany also was forced to pay large reparation payments to the Allies (who opposed Germany in the war). The German economy and national pride were deeply wounded. The Great Depression was worse in Germany than in America. The bad situation in Germany made it possible for a radical leader like Hitler, making all sorts of bold promises, to win over enough people to rise to power. Hitler promised a return to national greatness and fiercely rebuilt Germany as a military machine. The rise of Hitler and the Nazis brought about World War II in Europe.
The Treaty of Versailles also included provision for forming an international organization that would pursue peaceful resolutions to conflicts. That became the League of Nations.
LEAGUE OF NATIONS
An organization such as the League of Nations was the signature idea of US President Woodrow Wilson. He had laid out 14 Points for establishing and maintaining world peace following the Great War (World War I). Point #14 was the establishment of an international peacekeeping association. The Treaty of Versailles adopted that idea, and the League of Nations was established in 1920. [Notably, the United States never joined the League, because the US Senate did not ratify the Treaty of Versailles.]
The League of Nations had set out clear goals for what it intended to do. The main aims of the League were disarmament across nations, preventing war through collective security of the international community, settling disputes between countries through negotiation, and improving welfare of people around the globe. But it proved unable to meet those goals. The United Nations, formed after World War II, has similar goals, and has been more effective in its efforts -- though there are still plenty of people who criticize the UN's effectiveness.
