SECTOR OF FIRE A sector of fire (fig. 4-3) is an area of responsi-bility assigned to a squad, a platoon, or a crew-sewed weapon to be covered by fire. The squad sector of fire is divided into fire teams and individual sectors of fire to cover the entire squad sector by fire. Sectors of fire ensure mutual support by overlapping the individual and fire team sectors. Normally, the squad leader is not assigned an individual sector of fire since the primary duty in the defense is directing and controlling the squad. Located within each sector of fire are lateral and forward limits.

1. Lateral Limits: Readily identifiable terrain features are selected to show the line of sight along each side of the sector. Two stakes are firmly placed near the position of a weapon to show the lateral limits for periods of reduced visibility.

2. Forward Limits: The forward limit is established at the range at which the weapon will open fire. When possible, a terrain feature is selected to locate the forward limit. This allows the squad leader a method of control to open fire on the enemy at a precise time to maximize effectiveness.

Figure 4-3.- Sector of fire. 

FIGHTING POSITIONS A fighting position is a location on the ground from which fire is delivered by an individual, a fire unit (squad or fire team), or a crew-served weapon. Before you select a fighting position, the assigned sector of fire is carefully examined from various locations. Examining is done in the prone position to ensure effective coverage of the sector of fire. The positions must provide the following:

Desired support of the sector Good fields of fire Maximum use of available cover and concealment Facilitate effective fire control by the unit leader

Carefully examine assigned sectors of fire from the prone position, and then select a fighting position to ensure effective coverage of the sector. Primary, alternate, supplementary, and battle fighting positions must be established (fig. 4-4).

NOTE: Range cards must be completed for each fighting position. Range cards will be discussed further in this chapter.

Primary Fighting Position The primary fighting position is the best available position from which the assigned sector of fire can cover. Individuals, fire teams,

Figure 4-4.- Defensive firing positions. squads, and crew-served weapons are assigned primary positions.

Alternate Fighting Position Alternate positions are not normally assigned to individuals or squads within the platoon. They are used primarily by crew-served weapons. An alternate position is located so that a crew-served weapon can continue to cover the original assigned sector of fire when the primary position becomes unsuited for carrying out that mission.

Supplementary Fighting Position Supplementary positions are prepared to guard against attack from directions other than those from which the main attack is expected. A supplementary position is a secondary position that does not cover the same sector of fire as the primary position. Supplementary positions are for security reasons and ensure protection, when occupied against surprise enemy attack from an unexpected direction. Movements to supplementary positions and concealed routes are covered to avoid enemy detection.

Battle Position The battle position is where the main effort of defense is concentrated. Companies and platoons are assigned battle positions. The battle position is made up of a series of sectors of fire that support and interlock one another. Based on the battle position of the company, platoon battle positions are assigned a right and left limit of fire in which gunfire can be delivered.

PRINCIPAL DIRECTION Of FIRE (PDF) A principal direction of fire (PDF) is a specific direction within a sector of fire of a flat trajectory weapon including crew-seined weapons. The PDF is designated as the primary fire mission for that weapon. 

Never assign more than one PDF per weapon. Assign a PDF using a terrain feature. Using a stake to guide the PDF during reduced visibility is vital to the effective firing of a PDF (fig. 4-5).

The PDF is used as follows: 1. To cover a gap in a final protective line (FPL) of a crew-served weapon

2. To cover a specific terrain feature endangering the company or platoon battle position, such as draws,

Figure 4-5.- Principal direction of fire. that may seine as an avenue of approach or a hilltop that may serve as a possible enemy vantage point 3. To protect a crew-served weapon by firing across its front

4. To augment the band of flank fire placed immediately in front of the FEBA or the defensive line when them are no visible targets of opportunity to the front