This rise of empires, this coalescence of small groups of men into larger and larger political aggregates, has been the chief work of civilization, when looked at on its political side. Like all the work of evolution, this process has gone on irregularly and intermittently, and its ultimate tendency has only gradually become apparent. This process of coalescence has from the outset been brought about by the needs of industrial civilization, and the chief obstacle which it has had to encounter has been the universal hostility and warfare bequeathed from primeval times. The history of mankind has been largely made up of fighting, but in the careers of the most progressive races this fighting has been far from meaningless, like the battles of kites and crows. In the stream of history which, beginning on the shores of the Mediterranean Sea, has widened until in our day it covers both sides of the Atlantic and is fast extending over the remotest parts of the earth, — in this main stream of history the warfare which has gone on-has had a clearly discernible purpose and meaning. Broadly considered, this warfare has been chiefly the struggle of the higher industrial civilization in defending itself against the attacks of neighbours who had not advanced beyond that early stage of humanity in which warfare was chronic and normal.