Infantry Drills

FM 3-21.8 – Chapter 7 – Section III – Planning Considerations

Section III – Planning Considerations

7-28.     The warfighting functions are a group of tasks and systems united by a common purpose that Infantry leaders use to accomplish missions and training objectives. Planning, synchronization and coordination among the warfighting functions are critical for success. The warfighting functions are addressed in this section.


The Intelligence warfighting function consists of the related tasks and systems that facilitate understanding of the enemy, terrain, weather, and civil considerations. In offensive operations the Infantry platoon leader uses his intelligence, surveillance, reconnaissance (ISR) assets to study the terrain and confirm or deny the enemy’s strengths, dispositions, and likely intentions, especially where and in what strength the enemy will defend.  These assets also gather information concerning the civilian population within the AO to confirm or deny their numbers, locations, and likely intentions.

Movement and mANEUVER

7-29.     The movement and maneuver warfighting function consists of the related tasks and systems that move forces to achieve a position of advantage in relation to the enemy. The purpose of maneuver is to close with and destroy the defending enemy. Maneuver requires a base-of-fire element to suppress or destroy enemy forces with accurate direct fires and bounding elements to gain positional advantage over the enemy. When effectively executed, maneuver leaves enemy elements vulnerable by forcing them to fight in at least two directions, robbing them of initiative, and ultimately limiting their tactical options. Movement and maneuver are the means by which Infantry leaders mass the effects of combat power to achieve surprise, shock, momentum, and dominance.

7-30.     The platoon will likely focus on mobility during the movement phase of offensive operations and may be required to breach obstacles as part of an offensive operation. These obstacles may be protective (employed to assist units in their close-in protection), which the platoon is expected to breach without additional assets. Tactical obstacles, however, which block, disrupt, turn, or fix unit formations, normally require engineer assets to breach. Refer to FM 3-34.2, Combined-Arms Breaching Operations, for a more detailed discussion of breaching.


7-31.     The fire support warfighting function consists of the related tasks and systems that provide collective and coordinated use of Army indirect fires, joint fires, and offensive information operations. The platoon may be able to employ indirect fires from field artillery or company and or battalion mortars to isolate a small part of the enemy defense or to suppress the enemy on the objective. The platoon leader must always keep in mind the potential danger to friendly elements created by indirect fires used in support of the assault. He must ensure that the indirect fire assets always know the position and direction of movement of his platoon.


7-32.     The protection warfighting function consists of the related tasks and systems that preserve the force, so the Infantry leader can apply maximum combat power. Preserving the force includes protecting personnel, physical assets, and information of the Infantry platoon.  Areas included in protection at the Infantry platoon level are:

– Safety

– Fratricide avoidance

– Survivability

– Air and missile defense

– Force health protection


7-33.     The sustainment warfighting function includes related tasks and systems that provide support and services to ensure freedom of action, extend operational reach, and prolong endurance. The primary purpose of sustainment in the offense is to assist the platoon and company in maintaining momentum during the attack. Key sustainment planning considerations for the platoon leader during the offense include:

– High expenditure of ammunition for selected tactical tasks.

– Friendly casualty rate and how to evacuate the casualties to what locations.

– Availability of water and other mission-essential supplies before, during, and after actions on the objective.

Command and control

7-34.     The command and control warfighting function consists of the related tasks and systems that support Infantry leaders in exercising authority and direction. At the Infantry platoon and squad level, command and control refers to the process of directing, coordinating, and controlling a unit to accomplish a mission.  During offensive operations Infantry leaders must establish control measures to provide a way to direct and coordinate the platoon or squad’s movement.

7-35.     Control measures are directives given graphically or orally by a commander to subordinate commands to assign responsibilities, coordinate fires and maneuver, and control combat operations. Each control measure can be portrayed graphically. In general, all control measures should be easily identifiable on the ground. Leaders organize the battlefield by establishing control measures that dictate responsibility, control movement, and manage fires.

Area of Operation

7-36.     The area of operation (AO) is the basic control measure for assigning responsibility and conducting operations. An AO is a clearly defined geographical area with associated airspace where leaders conduct operations within the limits of their authority. Within an AO leaders are responsible for accomplishing their mission and are accountable for their unit’s actions. Units acting as part of a larger unit operate within the AO of the next higher commander. When assigned their own AO, leaders of Infantry platoons or squads usually have expanded planning, preparation, and execution responsibilities. At lower levels, the term AO is often synonymous with a unit’s current location and any associated operational environment, usually without formal boundaries.

7-37.     Boundaries control the maneuver and fire of adjacent units. They are normally drawn along recognizable terrain features and are situated so key terrain features and avenues of approach are inclusive to one unit.

7-38.     Leaders use boundaries as their basic control measure to divide up the battlefield and assign responsibilities. When given a boundary, the owning unit may employ any direct or indirect fire in accordance with previously-issued orders and ROE without receiving further clearance from the controlling headquarters. The following exceptions apply:

– Munitions that produce effects outside of the boundary must be authorized by higher.

– Munitions that are restricted  must authorized.

Direct Fire and Boundaries

7-39.     Direct fire may be used across a unit boundary without prior coordination if the enemy target is clearly identified. When possible, direct fire boundries should be coordinated with adjacent units. Unless the target poses an imminent threat, the leader authorizing the fire should attempt prior coordination before engaging targets across his boundary. Indirect fire will not be used across a unit’s boundary unless prior coordination is made.

Basic Control Measures

7-40.     Leaders use the boundary to divide up their AOs for subordinates. An AO normally contains one or more engagement areas (defense operations) and or objectives (offensive operations). Leaders use additional control measures to specify responsibilities, control movement and fires (direct and indirect), sequence subordinate activities, and synchronize other resources.

Types of AOs

7-41.     The type of AO is defined by whether a unit shares a boundary with an adjacent unit. If it does, it is a contiguous AO. If a boundary is not shared with another unit, it is a noncontiguous AO (Figure 7-6). The higher headquarters is responsible for the area between noncontiguous AOs.


Figure 7-6. Types of AOs.

Mutually Supporting Units

7-42.     Regardless of whether a unit shares a common boundary, leaders must determine if they have mutually-supporting adjacent units. The presence of a mutually-supporting unit indicates an increased requirement for coordination. A position without mutually-supporting adjacent units indicates an increased requirement for security—360-degree security.

Integrating Control Measures With Terrain

7-43.     When looking for terrain features to use as control measures, leaders consider three types: linear; point; and area. Linear features follow major natural and man-made features such as ridgelines, valleys, trails, streams, power lines, and streets. Point features can be identified by a specific feature or a grid coordinate including, hilltops, and prominent buildings. Area features are significantly larger than point features and require a combination of grid coordinates and terrain orientation. Table 7-2 lists common uses of terrain features for control measures.

Table 7-2. Terrain feature control measures.

Use of Linear Terrain Features in the Offense

Use of Point Terrain
Features in the Offense

Use of Area Terrain
Features in the Offense

Axis of advance

Direction of attack

Infiltration lane

Limit of advance

Line of contact

Line of departure

Phase line

Probable line of deployment


Check point

Coordination point

Linkup point

Point of departure

Rally point

Target reference point

Assembly area

Assault position

Battle position


Named area of interest

Targeted area of interest

Use of Linear Terrain Features in the Defense

Use of Point Terrain
Features in the Defense

Use of Area Terrain
Features in the Defense

Battle handover line

Final protective line

Forward edge of battle area

Forward line of own troops

Screen line

Guard line

Observation post

Target reference point

Battle position

Main battle area

Security zone



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