"The importance of war and military institutions has been generally neglected in British historical writing, whose tone has been set by the Whig and liberal emphasis on peaceful constitutional progress. In this liberal view war appears as an aberration, an interruption of a "natural" condition of peace: almost as a form of delinquency unworthy of intellectual attention. The liberal, pacifistic view of history can only be maintained by resolute aversion of the gaze from the facts. For conflict between tribal or social groups and nations constitutes the essential human condition in the absence of a world-state with a monopoly of force. The relations between nation states have always been those of a struggle for advantage and domination, where friendships may indeed burgeon while interests temporarily coincide, but then again languish when those interests diverge. Peace and war in history flow continually in and out of each other, alternative aspects of the single phenomenon of the struggle for power. It is false and unrealistic therefore to divide policy between hard-and-fast categories of "peace" and "war". Policy may shade all the way from trade and diplomatic rivalry through indirect conflict and limited war to total war; the distinctions are of degree, not of kind"