f physical conditions in the field of action may be
illustrated by any case where ends otherwise feasible of attainment
cannot be achieved without effecting changes in such conditions. The
resolution of the uncertainty then requires study to determine what
suitable changes can be made. Changes for such a purpose may take
various forms, such as the construction of physical features in the
area involved, or the destruction of such features already existing;
or, again, both methods may be employed. Examples of such changes have
existed and still exist in profusion, some of them, military and
non-military, being on such a scale as radically to alter the previous
status with respect to entire nations. The question as to what changes
ought to be effected in the prevailing physical conditions, in order
to attain a certain objective, can be answered by the application of
what may be called the principle for the determination of the proper
physical conditions to be established in the field of action,--as
follows:

In any human activity, the proper physical conditions to be
established in the field of action depend on fulfillment of the
requirements of

Suitability of such conditions to the end in view, as
determined by the factor of the appropriate effect
desired,

Feasibility of effort to establish such conditions, on the
basis of comparative resources, as determined by the
factors of the means available and opposed, influenced by
the factor of the physical conditions existing in the
field of action, and

Acceptability of the results of the effort involved, as
determined by the factor of the consequences as to costs.

* * * * *

The factor of consequences as to costs also calls for special notice.
The influence of this factor frequently justifies abandonment of
suitable ends in view, even though their attainment has been
determined to be feasible, because the loss involved would out-weigh
the gain. Immediate success may be attained at such cost as to prevent
the attainment of larger ends (see the discussion, pages 9 and 10, of
the relationship of strategy and tactics).

On the other hand, the circumstances of the case may well justify
loss, however great, because the alternative is unacceptable, even
though the consequences involve complete destruction. Moreover, the
need for swift and aggressive action in many act