In "Statistics of Deadly Quarrels", Richardson plotted the magnitude of conflicts (by death toll) and ended up with a statistical curve that was near a Poisson distribution. Assuming this trend continues, what should this mean for Pentagon planning? From a review of Richardson's book:
It's no surprise that the two World Wars of the 20th century are at the top of this list; they are the only magnitude-7 conflicts in human history. ... the remainder of the 315 recorded wars, along with all the thousands of quarrels of intermediate size, produced less than a fourth of all the deaths.
The list of magnitude-6 wars also yields surprises, although of a different kind. Richardson identified seven of these conflicts, the smallest causing half a million deaths and the largest about 2 million...
While planning for the Big One is traditional, the statistics imply that we should also expect a larger number of Smaller Ones that may require US-led intervention, and an even greater number of lower-intensity conflicts which may tie up significant resources due to sheer quantity. Iraq is likely not an exceptional case, but merely a conflict further down the curve.