Frequency of wars and geographical opportunity

between the frequency of wars and the size of wars may be derived on the basis of geographical opportunity alone. It is, of course, reasonable to expect geographical opportunity to affect the frequency of wars, since the frequency of wars between neighboring countries is greater than the frequency of wars between countries widely separated geographically. A man is much more likely to quarrel with his next-door neighbor than with someone several houses removed. Interactions of all sorts, both constructive as well as destructive, are more frequent between people in adjacent areas than between those widely separated geographically. If war is more likely betveen neighboring countries, then the frequency of wars experienced by a particular country should correlate with the number of neighbors the country has. Lewis Fry Richardson (1960, p. 176), showed that this was indeed the case. He found that the number of external