3-46. Usually, as part of a larger element, the Infantry platoon conducts the defense performing several integrated and overlapping activities. The following paragraphs focus on the tactical considerations and procedures involved in each activity. This discussion shows an attacking enemy that uses depth in its operations, but there will be situations where a platoon must defend against an enemy that does not have a doctrinal operational foundation. The platoon must be prepared to defend against such threats. This unconventional (insurgent or terrorist force) enemy situation requires a more flexible plan that allows for more responsive and decentralized control of combat power rather than spreading it evenly throughout the platoon’s area of operation. The platoon also may conduct ‘base-camp’ (Refer to FM 3-21.10 for more information.) or perimeter defense along with offense and patrolling against terrorist and insurgent forces. (Refer to chapter 6 of this publication for a discussion on patrol base activities.)
3-47. As the platoon leader plans his defense, he generally follows this order of events ─
Reconnaissance and surveillance (R&S) operations and enemy preparatory fires.
Occupation and preparation.
Approach of the enemy main attack.
Consolidation and reorganization.
RECONNAISSANCE AND SECURITY OPERATIONS AND ENEMY PREPARATORY FIRES
3-48. Security forces must protect friendly main battle area forces in order to allow them to prepare their defense. These security forces work in conjunction with and complement company and battalion security operations. The enemy will try to discover the defensive scheme of maneuver using reconnaissance elements and attacks by forward detachments and disruption elements. It also tries to breach the platoon’s tactical obstacles.
Army Sgt. from Reconnaissance Platoon looks through the scope of his rifle.
3-49. The security force’s goals normally include providing early warning, destroying enemy reconnaissance units, and impeding and harassing enemy assault elements. The security force continues its mission until directed to displace. The commander also may use security forces in his deception effort to give the illusion of strength in one area while establishing the main defense in another. While conducting this type of security operation, the Infantry platoon may simultaneously have to prepare battle positions, creating a challenging time-management problem for the commander and his subordinate leaders.
3-50. During this activity, the Infantry platoon might be required to provide guides to pass the security force and might be tasked to close the passage lanes. The platoon also may play a role in shaping the battlefield. The platoon leader may position the platoon to deny likely enemy attack corridors to enhance flexibility and force enemy elements into friendly engagement area. When it is not conducting security or preparation tasks, the platoon normally occupies hide positions to avoid possible CBRN strikes or enemy artillery preparation.
OCCUPATION AND PREPARATION
3-51. A leader's reconnaissance is critical during this time in order for the platoon to conduct occupation without hesitation and begin the priorities of work. The participants in the reconnaissance are the platoon leader, platoon sergeant, and selected squad leaders, forward observer, RTO, and a security element. The goals are, but not limited to, identification of enemy avenues of approach, engagement area, sectors of fire, the tentative obstacle plan, indirect fire plan, observation post, rally point and command post locations. Operational security is critical during the occupation to ensure the platoon avoids detection and maintains combat power for the actual defense. Soldiers, at all levels of the platoon, must thoroughly understand their duties and responsibilities related to the occupation; they must be able to execute the occupation quickly and efficiently to maximize the time available for planning and preparation of the defense.
APPROACH OF THE ENEMY MAIN ATTACK
3-52. The platoon engages the enemy at a time and place where direct and indirect fire systems are maximized to achieve success within his designated area of operation. If available, as the enemy's assault force approaches the engagement area, the platoon may initiate CAS to weaken the enemy. Friendly forces occupy their actual defensive positions before the enemy reaches direct fire range and may shift positions in response to enemy actions or other tactical factors.
Note. Long-range fires might be withheld in accordance with a higher commander's intent.
3-53. During an assault, the enemy deploys to achieve mass at a designated point, normally employing assault and support forces. This may leave him vulnerable to the combined effects of indirect and direct fires and integrated obstacles. The enemy may employ additional forces to fix friendly elements and prevent their repositioning. Friendly counterattack forces might be committed against the enemy flank or rear, while other friendly forces may displace to alternate, supplementary, or subsequent positions in support of the commander's scheme of maneuver. All friendly forces should be prepared for the enemy to maximize employment of combat multipliers to create vulnerabilities. The enemy also is likely to use artillery, CAS, and CBRN weapons to set the conditions for the assault.
3-54. The platoon engages the enemy. Squad leaders and team leaders control their Soldiers’ direct fires. Destroyed vital positions are reoccupied. Soldiers move to alternate positions if the primary positions become untenable. Casualties are evacuated. Mines, indirect fires to include mortars are fired. Javelins and other direct fire weapons target the enemy’s support positions.
3-55. Under limited visibility, selected mortars and field artillery units initially may fire infared illumination if the enemy has not identified the defenders’ positions. Once the platoon engages the enemy from its primary positions, regular illumination is used. If the platoon has overhead cover and the enemy penetrates the tactical wire, fires may include variable timed fuzed HE.
3-56. When required, final protective fires are initiated. Indirect fire systems to include FA and heavy mortars; join in firing their final protective fires concentrations until ordered to cease-fire or have exhausted their ammunition. Medium machine guns fire along their final protective lines (FPL). Soldiers fire to the flank to provide mutual support. Soldiers are resupplied with ammunition, and casualties evacuated.
3-57. As the enemy's momentum slows or stops, friendly forces may conduct a counterattack. The counterattack might be for offensive purposes to seize the initiative from the enemy. In some cases, the purpose of the counterattack is mainly defensive such as reestablishing a position or restoring control of the sector. The Infantry platoon may participate in the counterattack as a base-of-fire element―providing support by fire for the counterattack force―or as the actual counterattack force.
CONSOLIDATION AND REORGANIZATION
3-58. The platoon secures its defensive area by repositioning forces, destroying remaining enemy elements, processing EPW, and reestablishing obstacles. The platoon conducts all necessary sustainment functions as it prepares to continue the defense. Even when enemy forces are not actively engaging it, the platoon maintains awareness of the tactical situation and local security at all times. The platoon prepares itself for possible follow-on missions.