procedure distinctive of the second
step is preferable, when it is applicable to the particular problem.
Therefore, when a subsidiary plan is to be developed directly from a
basic Decision, this is frequently the better procedure. This comment
is applicable not only to battle plans but also to other subsidiary
plans such as sortie plans, entrance plans, and logistics plans. The
commander may find it necessary, however, to expand the study of
fighting strength made in Section I-B of the basic estimate, in order
to obtain the detailed data needed for formulating the subsidiary
plan.

In spite of the relative simplicity of the second-step method, cases
occur where the procedure of the first step is nevertheless
preferable. For example, a basic Decision making provision for a major
campaign, divided into stages of some scope, may involve, as part of
one of these stages, an operation to capture an island. Such an
operation may itself require a considerable effort on the part of the
whole force; yet the operation may be so specialized or localized, or
both, with reference to the entire effort contemplated in the basic
Decision, that the solution of this subsidiary problem can best be
accomplished through the procedure distinctive of the first step.

The commander will therefore necessarily be the judge, in each case,
as to the particular procedure to be adopted.

There are wide variations in the requirements of the Estimate Form,
when used for the solution of subsidiary problems. This is natural
because these problems vary widely in nature. They include, on the one
hand, problems dealing directly with the conflict of armed forces, for
which the Form is especially designed. On the other hand, these
problems include those dealing with the factors related to freedom of
action. To be suitable for this purpose, the Form requires
modification in varying degrees. Certain examples are included in the
latter part of this chapter (page 176 and following).

The application of the procedure of the first step to the solution of
such subsidiary problems requires provision for deriving, in each
case, a (subsidiary) mission appropriate to the problem. Of the two
elements of the mission, the (subsidiary) purpose is first determined,
because the (subsidiary) task will necessarily be suitable to the
(subsidiary) purpose. These elements of the (subsidiary) mission may
be obtained from one or more of the operations into which the basic
Decis