General. By the issue of directives, a commander communicates to his subordinates his plans or such parts of them as he desires. Directives may be oral or written, or may be transmitted by despatch. Whether a directive is to be effective upon receipt, or under specified conditions, or at a specific time, or upon further instructions from the commander, will be evident from its nature, or will be prescribed in the body of the directive itself. The manner of determining the details of a plan has been discussed in Chapter VII. The matter contained therein is pertinent to the preparation of a plan that is not to be issued as a directive as well as to one that is to be so issued. The various categories of directives customarily employed in our naval service, and standard forms for these, are described hereinafter. The essentials of a military directive which is designed to govern the execution of a plan are: (a) That it indicate the general plan for the common effort of the entire force. (b) That it organize the force with a view to the effective accomplishment of this plan. (c) That it assign tasks to the subdivisions of the force, such that the accomplishment of these tasks will result in the accomplishment of the plan adopted for the entire force. (d) That it make appropriate provision for coordination among subdivisions, for logistics support, and for the collection of information and the dissemination of intelligence, that it state the conditions under which the plan is to become effective; and that it indicate the location of the commander during the period of execution. Some of these essentials may have found their expression in previous instructions, or may be unnecessary because of the state of mutual understanding. On the other hand, the directive may include annexes in the form of alternative and subsidiary plans, letters of instructions (page 188), and other material designed to be of assistance in the intelligent accomplishment of the assigned task. In issuing a directive, whether written or oral, except such a fragmentary order as has previously been described (page 184), a commander has the following definite responsibilities: (a) To ensure that subordinates understand the situation,--therefore, to give them pertinent available information. (b) To set forth clearly the general plan to be carried out by his entire force, as well as the tasks to be accomplished by each subdivision of his force. (c) To provide each of these subdivisions with adequate means to accomplish its assigned task. (d) To allow subordinate commanders appropriate discretion within the limits of their assigned tasks, without, however, sacrifice of the necessary coordination.