t of
war is based are few and unchangeable, resembling in this the code of
morality; but their application varies with the theatre of the war, the
genius and temper of the people engaged, and the kind of arms employed"
(General R. Taylor, C.S. Army). "Although the manifold inventions of
modern times have given to warfare {2} a wider scope and fresh
materials, it remains obedient to the same laws as in the past; but it
applies these laws with means more numerous, more powerful, and more
delicate" (Marshal Foch). "This war has given us no new principles;
but different mechanical appliances--and in particular the rapid
improvement and multiplication of aeroplanes, the use of immense
numbers of machine guns and Lewis guns, the employment of vast
quantities of barbed wire as effective obstacles, the enormous
expansion of artillery, and the provision of great masses of motor
transport--have introduced new problems of considerable complexity
concerning the effective co-operation of the different arms and
services. Much thought has had to be bestowed upon determining how new
devices could be combined in the best manner with the machinery already
working" (Marshal Haig).

The laws of war are not in themselves difficult to understand, but
their successful application on the field of battle requires that they
should be carefully studied and considered in all their aspects. "The
mind can only be trained to this by close study of campaigns, and by
the solution of definite problems on maps and on the ground" (General
Sir E. B. Hamley). "A lifelong experience of military study and
thought has taught me that the principle of the tactical employment of
troops must be instinctive. I know that in putting the Science of War
into practice it is necessary that its main tenets should form, so to
speak, part of one's flesh and blood. In war there is little time to
think, and the right thing to do must come like a flash--it must
present itself to the mind as perfectly _obvious_" (Marshal French).
The same idea is expressed by the Generalissimo of the largest
victorious force that was ever controlled by one mind. "Generally
speaking, grave situations partially obscure even a bright intellect.
It is therefore with a fully equipped mind that one ought to start in
order to make war or even to understand {3} war. No study is possible
on the battlefield; one does there simply what one _can_ in order to
apply what one knows. In order to _do