Proponents state that this right acknowledges the status quo, and that denial of the right is meaningless unless one is able and willing to use military force to deny it. Further, the right was traditionally accepted because the conquering force, being by definition stronger than any lawfully entitled governance which it may have replaced, was therefore more likely to secure peace and stability for the people, and so the right of conquest legitimises the conqueror towards that end. The completion of colonial conquest of much of the world, the devastation of World War I and World War II, and the alignment of both the United States and the Soviet Union with the principle of self-determination led to the abandonment of the right of conquest in formal international law. The 1928 Kellogg–Briand Pact, the post-1945 Nuremberg Trials, the UN Charter, and the UN role in decolonization saw the progressive dismantling of this principle. Simultaneously, the UN Charter's guarantee of the "territorial integrity" of member states effectively froze out claims against prior conquests from this process.
After the attempted conquests of Napoleon and up to the attempted conquests of Hitler, the disposition of territory acquired under the principle of conquest had to, according to international law, be conducted according to the existing laws of war. This meant that there had to be military occupation followed by a peace settlement, and there was no reasonable chance of the defeated sovereign regaining the land. While a formal peace treaty "makes good any defects in title", it was not required. Recognition by the losing party was not a requirement: "the right of acquisition vested by conquest did not depend on the consent of the dispossessed state". However, the alternative was annexation which if protested as unlawful, a peace treaty was the only means to legitimize conquest in a time of war. Essentially, conquest itself was a legal act of extinguishing the legal rights of other states without their consent. Under this new framework, it is notable that conquest and subsequent occupation outside of war was illegal. In post-World War II times, when the international community frowned on wars of aggression, not all wars involving territorial acquisitions ended in a peace treaty. For example, the fighting in the Korean War paused with an armistice, without any peace treaty covering it. North Korea is still technically at war with South Korea and the United States as of 2020.
