The significance of the League of Nations in international diplomacy lay in its role as the first global attempt at collective security and conflict resolution following World War I. Established by the Treaty of Versailles in 1919, the League aimed to prevent future wars through diplomacy, disarmament, and negotiation. It represented a shift towards internationalism and cooperation among nations. Although it struggled with enforcement and credibility issues, the League laid the groundwork for future organizations, notably the United Nations, and underscored the importance of dialogue and multilateralism in preventing conflicts on a global scale.