On the march, as you overtake, or are joined by, the field trains of the troops, you will assume command. Hasten your march until you are clear of JEPSOM. SMITH, _Chief of Staff_. Copies to all Commanders. By Lieut. Jones to officer in charge of trains. Birmingham, 8 Sept. ’25, 9-50 a. m. To Captain Mott, commanding trains: Our advance guard met at 9-30 a. m. two battalions hostile infantry at GARLINGTON. Have trains keep well closed and follow main body without distance. NORTON, _Colonel, commanding_. The first two examples are of the formal type. The third one is less so. _Verbal orders_ are usually transmitted by officers. However, if the order consists of a single sentence such as, “The trains will halt two hours at Bingham,” it may be transmitted by an enlisted man. Although there is more latitude in the form of written _order_ than in that of the field order, the one should be as brief and unmistakable in its construction as the other. The paragraph structure and sequence should be as logical and unified as English composition can make them. With your book open at the extract from Field Service Regulations in regard to _the order_, compose enough imaginary _orders_ to cover all the instances therein given. LETTERS OF INSTRUCTION _Letters of Instruction_ chiefly differ from orders, operation orders, and field orders in their lack of definition of specific tactical duties. They are truly instructions. They deal mainly with strategic considerations and general plans, because the writer is usually far away from, or not in direct command of, the units which are going to carry out the general plans. At the beginning of campaigns _letters of instruction_ enumerate the troops of the various commands and the corresponding leaders. “In armies, combat orders will often be in the form of, or a part of, letters of instruction to the commanding generals in the field armies composing the army. But where the field armies are within supporting distance of each other and can mutually coöperate in the task assigned them, formal combat orders may be issued. Such orders are necessarily general in character and consist of a statement of the objective sought by the army commander, and of the part he expects each field army to play in attaining this objective. The army commander, either by means of letters of instruction or by personal conferences with his field army commanders, fully acquaints them not only with the immediate end in view, but also with so much of his future plans as may be necessary to insure thorough cooperation on their part.”[17]