for both parties, ended without disruption, in
the surrender of the weaker of the two, and after a time in a complete
reconciliation between them.

Thus war may arise between two parties in a single State, and when it
does the two parties become, to all intents and purposes, separate,
independent, and sovereign States for the time being, and are, for the
most part, so regarded and treated by other independent States not
taking part in the conflict. For this reason, though the origin of a
civil war may differ widely in all its circumstances and conditions from
that of a war between two separate States, sovereign and independent _ab
initio_, yet as soon as a state of war is established, as distinct from
that of a puny revolt or a petty rebellion, there is, for a student of
war, no practical difference between a civil war and any other kind of
war. Both fall under the definition of war as the armed conflict of
national wills.

Between two separate, sovereign, independent nations a state of war
arises in this wise. We have seen that the internal policy of an
independent State is subject to no direct external control. But States
do not exist in isolation. Their citizens trade with the citizens of
other States, seeking to exchange the products of their respective
industries to the advantage of both. As they grow in prosperity, wealth,
and population, their capital seeks employment in other lands, and their
surplus population seeks an outlet in such regions of the earth as are
open to their occupation. Thus arise external relations between one
State and another, and the interests affected by these relations are
often found--and perhaps still more often believed--by one State to be
at variance with those of another. In pursuit of these interests--which,
as they grow and expand, become embodied in great consolidated kingdoms,
great colonial empires, or great imperial dependencies, and tend to be
regarded in time as paramount to all other national interests--each
State formulates and pursues an external policy of its own which may or
may not be capable of amicable adjustment to the policy of other States
engaged in similar enterprises. It is the function of diplomacy to
effect adjustments such as these where it can. It succeeds much more
often than it fails. Conflicting policies are deflected by mutual
agreement and concession so as to avoid the risk of collision, and each
State, without abandoning its policy, modifies it and ad