=48. Right:= The right extremity or element of a body of troops. =49.= NOTE. In view of the fact that the word "Echelon" is a term of such common usage, the following definition is given: By echelon we mean a formation in which the subdivisions are placed one behind another, extending beyond and unmasking one another either wholly or in part.--Author. [Illustration: BATTALION IN ECHELON: COMPANIES UNMASKING WHOLLY] [Illustration: BATTALION IN ECHELON: COMPANIES UNMASKING IN PART] INTRODUCTION =50. Object of military training.= Success in battle is the ultimate object of all military training; success may be looked for only when the training is intelligent and thorough. (1) =51. Commanding officers accountable for proper training of organizations; field efficiency; team-work.= Commanding officers are accountable for the proper training of their respective organizations within the limits prescribed by regulations and orders. (2) The excellence of an organization is judged by its field efficiency. The field efficiency of an organization depends primarily upon its effectiveness as a whole. Thoroughness and uniformity in the training of the units of an organization are indispensable to the efficiency of the whole; it is by such means alone that the requisite team-work may be developed. =52. Simple movements and elastic formations.= Simple movements and elastic formations are essential to correct training for battle. (3) =53. Drill Regulations a Guide; their interpretation.= The Drill Regulations are furnished as a guide. They provide the principles for training and for increasing the probability of success in battle. (4) In the interpretation of the regulations, the spirit must be sought. Quibbling over the minutiae of form is indicative of failure to grasp the spirit. =54. Combat principles.= The principles of combat are considered in Pars. 50-363. They are treated in the various schools included in Part I of the Drill Regulations only to the extent necessary to indicate the functions of the various commanders and the division of responsibility between them. The amplification necessary to a proper understanding of their application is to be sought in Pars. 364-613. (5) =55. Drills at attention, ceremonies, extended order, field exercises and combat exercises.= The following important distinctions must be observed: (a) Drills executed at =attention= and the ceremonies are =disciplinary exercises= designed to teach precise and soldierly movement, and to inculcate that prompt and subconscious obedience which is essential to proper military control. To this end, smartness and precision should be exacted in the execution of every detail. Such drills should be frequent, but short.