An excerpt from a book by Norman Angell, (Nobel Peace Prize winner, lecturer, journalist and MP) in 1910 as to why wide scale war could not happen between major powers.

    [War] belongs to a stage of development out of which 
    we have passed that the commerce and industry of a 
    people no longer depend upon the expansion of its 
    political frontiers; that a nation's political and 
    economic frontiers do not now necessarily coincide; 
    that military power is socially and economically 
    futile, and can have no relation to the prosperity 
    of the people exercising it; that it is impossible 
    for one nation to seize by force the wealth or trade 
    of another -- to enrich itself by subjugating, or
    imposing its will by force on another; that in short,
    war, even when victorious, can no longer achieve those 
    aims for which people strive.