These limits apply to the original deployment of the brigade for combat and presuppose an enemy of equal or nearly equal training and morale. The limits necessitated by the subsequent progress of the combat can not be foreseen. 349. Units larger than the brigade are generally composed of all arms. Combined tactics are considered in the Field Service Regulations. PART II.--COMBAT. INTRODUCTION. 350. Part II of these regulations treats only of the basic principles of combat tactics as applied to infantry and to the special units, such as machine guns and mounted scouts, which form a part of infantry regiments and battalions. The combat tactics of the arms combined are considered in Field Service Regulations. 351. Modern combat demands the highest order of training, discipline, leadership, and morale on the part of the infantry. Complicated maneuvers are impracticable; efficient leadership and a determination to win by simple and direct methods must be depended upon for success. 352. The duties of infantry are many and difficult. All infantry must be fit to cope with all conditions that may arise. Modern war requires but one kind of infantry--good infantry. 353. The infantry must take the offensive to gain decisive results. Both sides are therefore likely to attempt it, though not necessarily at the same time or in the same part of a long battle line. In the local combats which make up the general battle the better endurance, use of ground, fire efficiency, discipline, and training will win. It is the duty of the infantry to win the local successes which enable the commanding general to win the battle. 354. The infantry must have the tenacity to hold every advantage gained, the individual and collective discipline and skill needed to master the enemy's fire, the determination to close with the enemy in attack, and to meet him with the bayonet in defense. Infantry must be trained to bear the heaviest burdens and losses, both of combat and march. Good infantry can defeat an enemy greatly superior in numbers, but lacking in training, discipline, leadership, and morale. 355. It is impossible to establish fixed forms or to give general instructions that will cover all cases. Officers and noncommissioned officers must be so trained that they can apply suitable means and methods to each case as it arises. Study and practice are necessary to acquire proper facility in this respect. Theoretical instruction can not replace practical instruction; the former supplies correct ideas and gives to practical work an interest, purpose, and definiteness not otherwise obtainable. 356. After the mechanism of extended order drill has been learned with precision in the company, every exercise should be, as far as practicable, in the nature of a maneuver (combat exercise) against an _imaginary_, _outlined_, or _represented_ enemy.