This duty of self-assertion is by no means satisfied by the mere repulse of hostile attacks; it includes the obligation to assure the possibility of life and development to the whole body of the nation embraced by the State.
Strong, healthy, and flourishing nations increase in numbers.

From a given moment they require a continual expansion of their frontiers, they require new territory for the accommodation of their surplus population.
Since almost every part of the globe is inhabited, new territory must, as a rule, be obtained at the cost of its possessors--that is to say, by conquest, which thus becomes a law of necessity.
The right of conquest is universally acknowledged.

At first the procedure is pacific.

Over-populated countries pour a stream of emigrants into other States and territories.

These submit to the legislature of the new country, but try to obtain favourable conditions of existence for themselves at the cost of the original inhabitants, with whom they compete.