For a comprehensive guide concerning security, download the Army Field Manual No. 7-8.
Here is an excerpt:
1-2. COMBAT POWER
The doctrine that guides infantry forces is based on the four elements of combat power: maneuver, firepower, protection, and leadership.
a. Maneuver. Maneuver is the movement of forces supported by fire to achieve a position of advantage from which to destroy or threaten destruction of the enemy. Infantry forces move to gain a position of advantage over the enemy and to hold that advantage. They maneuver to attack enemy flanks, rear areas, logistics points, and command posts. In the defense, they maneuver to counterattack a flank of the enemy attack. Maneuver, properly supported by fires, allows the infantry to close with the enemy and gain a decision in combat.
b. Firepower. Firepower is the capacity of a unit to deliver effective fires on a target. Firepower kills or suppresses the enemy in his positions, deceives the enemy, and supports maneuver. Without effective supporting fires the infantry cannot maneuver. Before attempting to maneuver, units must establish a base of fire. A base of fire is placed on an enemy force or position to reduce or eliminate the enemy’s ability to interfere with friendly maneuver elements. Leaders must know how to control, mass, and combine fire with maneuver. They must identify the most critical targets quickly, direct fires onto them,
and ensure that the volume of fires is sufficient to keep the enemy from returning fire effectively, and the unit from expending ammunition needlessly.
c. Protection. Protection is the conservation of the fighting potential of a force so that it can be applied at the decisive time and place. Units must never permit the enemy to acquire an unexpected advantage. Platoons and squads take active and passive measures to protect themselves from surprise, observation, detection, interference, espionage, sabotage, or annoyance. Protection includes two basic considerations: care of the soldier and his equipment, and action to counter enemy combat power.
(1) The first consideration involves sustainment techniques necessary to maintain the platoon and squads as an effective fighting force. It includes keeping soldiers healthy to maintain fighting morale through personal hygiene, physical conditioning, and rest plans. It also includes keeping equipment in good working condition, and providing and protecting supplies. It means managing the soldier’s load so that he carries only what is needed and is fit to fight when required.
(2) The second involves security, dispersion, cover, camouflage, deception, and suppression of enemy weapons. Ultimately, the infantryman must remain undetected to survive. Once found, the infantryman becomes vulnerable to all the fires of the enemy and he must either fight to break contact or to close with and finish the enemy. The infantry always wants to set the time and place of battle, and must protect itself so that it can do so with maximum combat power and the important element of surprise.
d. Leadership. Military leadership is a process by which a soldier influences others to accomplish the mission. Leaders coordinate the other three elements of combat power. Their competent and confident leadership results in effective unit action. The right leadership gives purpose, direction, and motivation in combat. Leaders must know their profession, their soldiers, and the tools of war. Only this kind of leader can direct soldiers to do difficult tasks under dangerous and stressful conditions.