The subjugated nation does not recognize this right of subjugation, and the more powerful civilized nation refuses to admit the claim of the subjugated to independence.
This situation becomes peculiarly critical when the conditions of civilization have changed in the course of time.

The subject nation has, perhaps, adopted higher methods and conceptions of life, and the difference in civilization has consequently lessened.

Such a state of things is growing ripe in British India.
Lastly, in all times the right of conquest by war has been admitted.

It may be that a growing people cannot win colonies from uncivilized races, and yet the State wishes to retain the surplus population which the mother-country can no longer feed.

Then the only course left is to acquire the necessary territory by war.