Right of conquest

The right of conquest is the purported right of a conqueror to territory taken by force of arms. It was sometimes considered a principle of international law from the 16th to the early 20th centuries. Its defenders state that the acknowledgement of this right is simply an acknowledgement of the status quo, and that denial of the right is meaningless unless one is able and willing to use military force to deny it. Furthermore, they note that granting such a right promotes peace, since it removes the justification for many wars by denying the legitimacy of violating the borders of a nation's de facto area of control. Also, historically strength in battle and fitness to command were not considered separate, (see Trial by Combat, and The Divine Right of Kings.)
See more at Wikipedia.org...