One of the most influential books ever written - it was used to develop military and social planning for a hundred years after it was published. Although some of its conclusions are questionable (and certainly technology has invalidated much of the thinking presented here), it is ideal for the gamer who is trying to approximate how a military or political leader will be making their decisions in peacetime and in wartime - through deciding how their navies will be used.
As always, the e-book is completely free through Google Books.
