If an Advanced Guard is unexpectedly attacked during the night, or meets with the Enemy, it has no other choice but instantly to fall upon him. The Non-Commissioned Officer must be instructed to disperse, in such a case, to the right and left, and to fire as much as possible; but the Officer advances rapidly with his Division, and charges. This is the only way to give time to the column to prepare for an attack. It is an unpardonable fault in an Advanced Guard to be frightened, and to retire upon the column, every thing will then be in confusion, and it would have been better, if there had been no Advanced Guard at all; but if it advanced with intrepidity the column has time. Should the Advanced Guard be obliged, by a superior force, to retire, after having fought bravely, this retreat ought to be made on either side of the Column, but never on the Column, because the latter would be fired upon, and the confusion increased. On all these subjects the men should be previously well instructed. Every Commanding Officer of a detached party must consider it as one of his first duties to give clear and circumstantial instructions to his men, without which they will frequently act contrary to his ideas, even with the best intention. III. REAR GUARD Is told off in separate divisions, the same as an Advance Guard, only in reverse order (fig. 4.) [Illustration: _Fig. 4._] The object of a Rear Guard is to prevent the enemy's approaching the column unperceived; two men in the Rear are sufficient, but these must be picked men. When the march is undisturbed, they often halt on the heights so as just to be able to look over to the rear, to discover the enemy. When a mountain is near, the Officer will do well to ride on the top of it, and to look about the country with his spy-glass.