Right of conquest

The right of conquest is the right of a conqueror to territory taken by force of arms. It was traditionally a principle of international law which has in modern times gradually given way until its proscription after the Second World War when the crime of war of aggression was first codified in the Nuremberg Principles and then finally, in 1974, as a United Nations resolution 3314.

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 (see the Scramble for Africa), 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.

Conquest and military occupation
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. If there was a territorial cession, then there had to be a formal peace treaty.

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 ended in an armistice, without any peace treaty covering it.