I don't know if anyone has read this, or what the opinion about it is among the Quiet Professionals, but there is a free, downloadable version of the 1940
Small Wars Manual available
here.
There is also a front page segment in today's (Thu, 08APR04) WSJ about the manual, including some interesting commentary from both proponents and detractors about its relevancy today. The article also contains some interesting history of the manual.