ion has been resolved. They may also be obtained from a preceding
subsidiary problem, already solved.

In illustration of the preceding, discussion is first centered on a
strategical problem of usual type, involving a subsidiary tactical
problem calling for the detailed employment of weapons in a naval
engagement. Other illustrations will deal with subsidiary problems
relating to particular aspects of freedom of action.

In the first example it is supposed that the commander has already
solved a basic problem of broad strategical scope, and has arrived at
a Decision which contemplates an engagement. A further logical act of
planning is now to develop a Battle Plan. Such development involves
the solution of a subsidiary problem. In this case the commander is
supposed to have found it desirable to solve this subsidiary problem
by the procedure distinctive of the first step.

In this problem, the situation summarized is an imaginary one. It may
eventuate either through the natural future developments of the
situation existing at the time of the solution of the basic problem,
or it may confront the commander during the execution of the plans
derived from the Decision of that (basic) problem. The Battle Plan
finally to be formulated will be for use under the conditions assumed
in this situation.

The commander will desire to draw up a Battle Plan as a provision for
the situation which he believes most likely to eventuate. However, as
he cannot be certain that this situation will occur, he may also
desire to assume other situations, i.e., prepare in advance for other
contingencies. It is then necessary for him to solve several problems,
each differing from the others in the assumptions (page 155) as to the
form the situation may take. The summary of the situation therefore
requires a brief statement of the conditions which are assumed. In
addition, such parts of the basic problem may be included as are
deemed pertinent to the new problem in hand.

In his new problem the purpose of the (subsidiary) mission may readily
be obtained from the basic problem. Suppose the assigned task,
motivating the estimate of the basic problem, to have been to "prevent
enemy convoy from reaching destination". This, the motivating task of
the basic problem, then becomes a suitable (subsidiary) purpose for
the mission of the subsidiary problem.

For the mission of the subsidiary problem, a motivating task, suitable
to the purpose thus determ