Trygve Lie's appointment as the first Secretary-General of the United Nations was a landmark moment in the early days of post-World War II international relations. Chosen during the inaugural session of the UN General Assembly in New York City, Lie was a seasoned diplomat with experience as Norway's Minister of Foreign Affairs. His election to the position was hailed as a step towards fostering collaboration and dialogue among nations aimed at preventing future conflicts. He assumed office in a world still reeling from the devastation of global warfare, and his selection was seen as a commitment to moral leadership and the sanctity of diplomacy.

Under Lie’s management, the United Nations faced numerous challenges, including the organization of peacekeeping efforts, the resolution of territorial disputes, and the coordination of refugee assistance. His role required navigating complex geopolitical landscapes and working with divergent national interests. Lie’s tenure set a precedent for future secretaries, establishing the UN Secretariat as a powerful tool for advocacy and conflict resolution in the international arena.

Despite the slow start, the post-war period and Lie's leadership helped solidify the UN's responsibility as a mediator in global affairs. Throughout his term, he championed the principles enshrined in the UN Charter, which promoted peace, security, and cooperation among member states.