By now Randolph Bourne's observation that "war is the health of the state" ought to be such a cliche that it would hardly need to be said. And yet, it must be said -- often -- because many still haven't gotten the word. If the state is the adversary of liberty, as it nearly always has been, then it follows that war is also the ill health of liberty. And when one thinks of war, one ought also to think of conscription because it's often somewhere close by. In a perverse way, Americans have been lucky. The divisive decade-long Vietnam war and access to the latest war-making technology have made...