\ \ -69= even if it does not prevent the actual outbreak of hostilities, It is, for reasons which will presently be indicated, highly unlikely that such a situation will occur, But even if it did occur, the shadow of the atomic bomb would so govern the strategic and tactical dispositions of either side as to create a wholly novel form of war, The kind of spatial concentrations of force by which in the past great decisions have been achieved would be considered too risky. The whole economy of war would be affected, for even if the governments were willing to assume responsibility for keeping the urbanpopulations in their homes, the spontaneous exodus of those populations from the cities might reach such proportions as to make it difficult to service the machines of war,. The conclusion is inescapable that war will be vastly different because of the atomic bomb whether or not the bomb is actually used. oeam aN tw : bes But let us now consider the degree of probability snverent in each of the three main situations which might follow from a a, prevent a major war. These three situations may be listed as follows: (a) a war fought without atomic bombs or other forms of radioactive energy; (b) a war in which atomic bombs were introduced only considerably after the outbreak of hostilities; (c) a war in which atomic bombs were used at or near the very outset of hostilities, We are assuming that this hypothetical conflict occurs at a time when each of the opposing sides possesses at least the "know-how" of bomb production, a situation Which, as argued in the previous chapter, approximates the realities to be expected not more than five to ten years hence, Under such conditions the situation described under (a) above could obtain only as a result of a mutual fear of retaliation, perhaps supported by inter~ national instruments outlaving the bomb as a weapon of war, It would not be