It is remarkable how large
a part of the best Christian works on the ethics of war is based on the
precepts of pagan moralists, and although in antiquity as in modern
times the real cause of war was often very different from the pretexts,
the sense of justice in war was as clearly marked in Roman as in most
Christian periods.[27]

Great stress was laid upon the duty of a formal declaration of war
preceding hostilities. Polybius mentions the reprobation that was
attached in Greece to the AEtolians for having neglected this custom. It
was universal in Roman times, and during the mediaeval period the custom
of sending a challenge to the hostile power was carefully observed. In
modern times formal declaration of war has fallen greatly into
desuetude. The hostilities between England and Spain under Elizabeth,
and the invasion of Germany by Gustavus Adolphus, were begun without any
such declaration, and there have been numerous instances in later
times.[28]

The treatment of prisoners has been profoundly modified. Quarter, it is
true, has been very often refused in modern wars to rebels, to soldiers
in mutiny, to revolted slaves, to savages who themselves give no
quarter. It has been often--perhaps generally--refused to irregular
soldiers like the French Francs-tireurs in the War of 1870, who without
uniforms endeavoured to defend their homes against invasion. It was long
refused to soldiers who, having rejected terms of surrender, continued
to defend an indefensible place, but this severity during the last three
centuries has been generally condemned. But, on the whole, the treatment
of the conquered soldier has steadily improved. At one time he was
killed. At another he was preserved as a slave. Then he was permitted to
free himself by payment of a ransom; now he is simply kept in custody
till he is exchanged or released on parole, or till the termination of
the war. In the latter half of the present century many elaborate and
beneficent regulations for the preservation of hospitals and the good
treatment of the wounded have been sanctioned by international
agreement. The distinction between the civil population and combatants
has been increasingly observed. As a general rule non-combatants, if
they do not obstruct the enemy, are subjected to no further injury than
that of paying war contributions and in other ways providing for the
subsistence of the invaders. The wanton destruction of private property
has been more and