Usmc defensive operations

Usmc defensive operations DEFAULT

Defence in depth

Military strategy where a defender delays and spreads out an attacker's advance

For a non-military "defence in depth", see Defence in depth (non-military).

For nuclear technology, see Defense in depth (nuclear engineering).

See also: Defence-in-depth (Roman military)

Defence in depth (also known as deep defence or elastic defence) is a military strategy that seeks to delay rather than prevent the advance of an attacker, buying time and causing additional casualties by yielding space. Rather than defeating an attacker with a single, strong defensive line, defence in depth relies on the tendency of an attack to lose momentum over time or as it covers a larger area. A defender can thus yield lightly defended territory in an effort to stress an attacker's logistics or spread out a numerically superior attacking force. Once an attacker has lost momentum or is forced to spread out to pacify a large area, defensive counter-attacks can be mounted on the attacker's weak points, with the goal being to cause attrition or drive the attacker back to its original starting position.


A conventional defence strategy would concentrate all military resources at a front line, which, if breached by an attacker, would leave the remaining defenders in danger of being outflanked and surrounded and would leave supply lines, communications, and command vulnerable.

Defence in depth requires that a defender deploy their resources, such as fortifications, field works and military units at and well behind the front line. Although attackers may find it easier to breach the more weakly defended front line, as they advance, they continue to meet resistance. As they penetrate deeper, their flanks become vulnerable, and, should the advance stall, they risk being enveloped.

The defence in depth strategy is particularly effective against attackers who are able to concentrate their forces and attack a small number of places on an extended defensive line.

Defenders that can fall back to a succession of prepared positions can extract a high price from the advancing enemy while themselves avoiding the danger of being overrun or outflanked. Delaying the enemy advance mitigates the attacker's advantage of surprise and allows time to move defending units to make a defence and to prepare a counter-attack.

A well-planned defence in depth strategy will deploy forces in mutually supportive positions and in appropriate roles. For example, poorly trained troops may be deployed in static defences at the front line, whereas better trained and equipped troops form a mobile reserve. Successive layers of defence may use different technologies against various targets; for example, dragon's teeth might present a challenge for tanks but is easily circumvented by infantry, while another barrier of wire entanglements has the opposite effects on the respective forces. Defence in depth may allow a defender to maximise the defensive possibilities of natural terrain and other advantages.

The disadvantages of defence in depth are that it may be unacceptable for a defender to plan to give ground to an attacker. This may be because vital military or economic resources are close to the front line or because yielding to an enemy is unacceptable for political or cultural reasons. In addition, the continuous retreats that are required by defence in depth require the defender to have a high degree of mobility in order to retreat successfully, and they assume that the defender's morale will recover from the retreat.


A possible early example of this came at the Battle of Cannae in 216 BC, when Hannibal employed this manoeuvre in order to encircle and destroy eight Roman legions, but that is disputed by some historians.[1]

Edward Luttwak used the term to describe his theory of the defensive strategy employed by the Late Roman army in the 3rd and 4th centuries AD.

Later examples of defence in depth might be European hill forts and the development of concentric castles. In those examples, the inner layers of defence can support the outer layers with projectile fire and an attacker must breach each line of defence in turn with the prospect of significant losses, and the defenders have the option of falling back to fight again. On a strategic level, defence in depth was employed by the Byzantine military.

In the American Revolutionary War's Battle of Cowpens, the American forces were positioned in three lines which soaked up the shock of the British charge and inflicted heavy casualties before the Americans were able to overrun the British who, at this point, had lost their cohesion.

More recent examples of defence in depth include the multiple lines of trenches of the First World War and the following Turkish War of Independence where the Turks stopped the advance of the Greeks towards Ankara. Also plans for the defence of Britain against a potential German invasion in the Second World War. During the Battle of Normandy, Wehrmacht forces utilized the bocage of the area, flooding of fields, and strategic placement of defences to create successive lines of defences to slow the attacking Allies in hopes that reinforcements would arrive.

The Pacific Theatre also had many examples of defence in depth, with the Japanese inflicting heavy casualties on the Americans in the Battles of Tarawa, Saipan, Peleliu, Iwo Jima, and Okinawa.

The best modern example of a successful defence in depth is that of the Battle of Kursk. During the battle, the Red Army deliberately drew the Germans into an attritional battle in multiple, well-prepared defensive lines, before launching massive counter-attacks on either side of the 9th Army in the north and the 4th Panzer Army in the south. The initial German offensive never fully penetrated the Red Army lines. By contrast, the subsequent Red Army counter-offensive pushed the front line hundreds of miles westwards.

Colonel Francis J. Kelly discussed the employment of defence in depth in Army Special Forces camps during the Vietnam War. Kelly, a former U.S. Army Special Forces commander and author of Vietnam Studies U.S. Army Special Forces 1961–1971, stated in his work that the austere Special Forces fighting camps were highly functional and easily defended.[citation needed]

While untested, this was also the planned NATO strategy in Europe during the Cold War at the Fulda Gap.[citation needed]

Application to other fields[edit]

Main article: Defence in depth (non-military)

Further information: Defense in depth (nuclear engineering)

The concept of Defence-in-Depth (DiD) is also applied in the fields of life-threatening technologies where it is critical to avoid a disaster, or to save lives.

The safety of nuclear reactors and radioactive waste repositories also fundamentally relies on multiple systems and redundant barriers. The principle of redundancy is essential to prevent the occurrence of dramatic failures and in case where a failure would develop to retard the progression of a potentially disastrous event and to give extra time for taking again the control of the failed system. Ultimately, if a failure cannot be avoided, DiD also contributes to mitigate the consequences and to attenuate the negative impacts of the failure.

Defence-in-Depth is required to guarantee the robustness of vital systems, e.g. in nuclear technologies and for aerospace systems where safety is critical. The DiD approach can be applied to any sensitive technology: submarines and naval systems, biotechnology, pharmaceutic industry, informatics, bank and financial systems, etc.

In nature, the immune system of most evolved organisms also appeals to multiple lines of defence in case a pathogen would defeat the first line of defence of cells, tissues and organs.

The robustness of the scientific method also relies on multiple lines of evidence and multiple lines of reasoning: strong claims require strong and multiple evidence. The repeatability and the reproducibility of experimental and calculations results are essential to guarantee their robustness and correctness. This associated with the scientific questioning and a constant interrogative attitude is at the core of the self-correcting process guiding the science.

Academics from Oxford University's Future of Humanity Institute also applied the concept of defence in depth to designing strategies for the prevention of existential catastrophes, especially those involving human extinction.[2]

See also[edit]


  1. ^Healy, Mark. Cannae: Hannibal Smashes Rome's Army. Sterling Heights, Missouri: Osprey Publishing, 1994.
  2. ^Cotton‐Barratt, Owen; Daniel, Max; Sandberg, Anders (2020). "Defence in Depth Against Human Extinction: Prevention, Response, Resilience, and Why They All Matter". Global Policy. 11 (3): 271–282. doi:10.1111/1758-5899.12786. ISSN 1758-5899. PMC 7228299. PMID 32427180.

TSULC: Defensive Operations [Image 1 of 6]

TSULC: Defensive Operations

A U.S. Marine with the Special Purpose Marine Air-Ground Task Force-Crisis Response-Africa 20.1, Marine Forces Europe and Africa, looks down his rifle’s sights during defensive operations at Morón Air Base, Spain, March 25, 2020. Marines are participating in a two-week leadership course to improve their leadership skills and work within a simulated forest environment. SPMAGTF-CR-AF is deployed to conduct crisis-response and theater-security operations in Africa and promote regional stability by conducting military-to-military training exercises throughout Europe and Africa. (U.S. Marine Corps photo by Cpl. Kenny Gomez)

Date Taken:03.26.2020
Date Posted:04.06.2020 08:26
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Location:MORóN AIR BASE, ES 

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This work, TSULC: Defensive Operations [Image 6 of 6], by Sgt Kenny Gomez, identified by DVIDS, must comply with the restrictions shown on

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Center for Strategic & International Studies

March 25, 2020

This commentary has been updated to incorporate material from the Marine Corps’ Force Design 2030 report.

Last July, General Berger electrified the national security community with planning guidance that proposed to align the Marine Corps with the National Defense Strategy (NDS) by making major changes to forces, equipment, and training. Though dramatic in concept, the guidance lacked specifics. General Berger has now provided those specifics, and they are as radical as the concepts. Gone are tanks and capabilities for sustained ground combat and counterinsurgency. Instead, the corps focuses on long-range and precision strike for a maritime campaign in the Western Pacific against China. But this new Marine Corps faces major risks if the future is different from that envisioned or if the new concepts for operations in a hostile environment prove more difficult to implement than the Marine Corps’ war games indicate.


For many years, strategists have yearned to refocus the military services on the Pacific and China. China, with its growing economy, modernizing military, and evident desire to reassert regional hegemony, has loomed as the primary long-term challenge to the United States. The Obama administration talked about a “rebalance” to the Pacific but was unable to put many specifics against the concept before it was dragged back to Europe and the Middle East in 2014 with the Russian occupation of Crimea and ISIS’s campaign in Syria and Iraq.

The Trump administration’s NDS focused on great power competition with China or Russia, —but China seemed to have priority. In 2019, acting secretary of defense Patrick Shanahan stated that DOD’s focus was “China, China, China.” To meet this new challenge, the NDS called for changes in military forces: “We cannot expect success fighting tomorrow’s conflicts with yesterday’s weapons or equipment.” The NDS also signaled that modernization was more important than the size of the force, implying a willingness to get smaller in order to build the capabilities needed for great power conflict. However, the NDS was vague on specifics about what changes were required, and many observers criticized the administration for not making sufficient changes in subsequent budgets.

General Berger’s Guidance

General David Berger became commandant of the Marine Corps on July 11, 2019. He immediately published his Commandant’s Planning Guidance , which laid out his vision for where the Marine Corps needed to go. New service chiefs typically produce such documents, but most are exhortations to seek excellence in the services’ traditional missions and to implement a few targeted reforms that the new chief desires to focus on. General Berger’s vision was different in that it implied major changes in many areas.

This vision aligned with the NDS and focused exclusively on China. This was not surprising since General Berger had commanded Marine forces in the Western Pacific. The vision sought to meld the Marine Corps’ traditional “force in readiness” role with that of readiness for great power conflict: “The Marine Corps will be trained and equipped as a naval expeditionary force-in-readiness and prepared to operate inside actively contested maritime spaces in support of fleet operations.”

Central to Berger’s vision is the ability to operate within an adversary’s (read China’s) bubble of air, missile, and naval power (which the Marine Corps calls the weapons engagement zone, or WEZ). The concept is that the Marine Corps will be a “stand-in force” that will operate within this WEZ, not a stand-off force that must start outside and fight its way in. As the guidance states: “Stand-in forces [are] optimized to operate in close and confined seas in defiance of adversary long-range precision ‘stand-off capabilities.’”

This requires developing “low signature, affordable, and risk worthy platforms” because existing ships and aircraft are the opposite—highly capable but expensive, few, and highly visible.

Another element of the new concept is “distributed operations,” the ability of relatively small groups to operate independently rather than as part of a large force, as in previous wars. “We recognize that we must distribute our forces ashore given the growth of adversary precision strike capabilities . . . and create the virtues of mass without the vulnerabilities of concentration. ” Thus, small Marine forces would deploy around the islands of the first island chain and the South China Sea, each element having the ability to contest the surrounding air and naval space using anti-air and antiship missiles. Collectively, these forces would attrite Chinese forces, inhibit them from moving outward, and ultimately, as part of a joint campaign, squeeze them back to the Chinese homeland.

A third element was institutional: the Marine Corps would leave sustained ground combat to the Army and focus on the littorals. Ground wars in the Middle East, North Korea, and Europe would be Army responsibilities.

The final element was political: General Berger judged that defense budgets are likely to be flat for the foreseeable future. “My assumption is flat or declining [budgets], not rising. . . . If [an increase] happens, great, but this is all built based on flat or declining [budgets].” Thus, unlike in the previous five years, when rising budgets allowed new investment and stable force levels, trade-offs would now be necessary. If the Marine Corps wanted to invest in new capabilities, it had to cut some existing units.

The Implementation

General Berger’s guidance proposed new concepts and approaches but lacked specifics. At the time, he noted that the Marine Corps was conducting analysis and war games and would later lay out how it would implement the guidance. Details of that implementation are becoming clearer with a short press release, a major report in the Wall Street Journal, and, finally, a Marine Corps 13-page report, Force Design 2030.

Implementation will be a 10-year effort that makes the radical changes that the guidance implied. The restructured Marine Corps will focus single-mindedly on a conflict with China in the Western Pacific, build capabilities for long-range and precision engagement in a maritime campaign, eliminate capabilities for counterinsurgency and ground combat against other armies, and get smaller to pay for the new equipment. The table below captures by element what the planning guidance said, what the Marine Corps has now, where it will move to, and what that means. (For a detailed discussion of current Marine Corps plans and structure, see CSIS U.S. Military Forces in FY 2020: Marine Corps . A few of the planning guidance items come from General Berger’s December article in War on the Rocks.)


The Risks

Radical change brings risks, and this effort is no different. Risks arise from the lack of hedging, the movement away from current operations, and the uncertain viability of the new war-fighting concepts. If the Marine Corps has misjudged the future, it will fight the next conflict at a great disadvantage or, perhaps, be irrelevant.

No Hedging

When these proposed changes are fully implemented, the Marine Corps will be well structured to fight an island campaign in the Western Pacific against China. Although the NDS allows hedging against other adversaries and conflicts—North Korea, Iran, counterterrorism—the Marine Corps does not plan to do that. As General Berger stated in his guidance: “[This] single purpose-built future force will be applied against other challenges across the globe; however, we will not seek to hedge or balance our investments to account for those contingencies.”

The lack of hedging means that the Marine Corps will not field the broad set of capabilities it has in the past. It will be poorly structured to fight the kind of campaigns that it had to fight in Korea, Vietnam, and Iraq. The history of the last 70 years has been that the United States deters great power conflict and fights regional and stability conflicts. Although forces can adapt, as seen during the long counterinsurgency campaigns in the Middle East, there is a delay and an initial lack of expertise. The Marine Corps might plan to defer these conflicts to the Army, but that has not worked in the past. Army forces have been too small to keep the Marine Corps out of sustained ground combat.

Marine Corps officials have argued privately that other kinds of conflicts would be lesser included capabilities of this focus on high-end conflict in the Western Pacific. This is misplaced. History is littered with examples of militaries that prepared for one kind of conflict and then had to fight a very different kind of conflict. In the best circumstances, militaries adapt at the cost of time and blood. In the worst circumstances, the result is catastrophic failure.

For example, in the 1950s and early-1960s the U.S. Army focused on great power conflict in Europe against the Soviet Union and the Warsaw Pact. That Army then had to fight a counterinsurgency conflict in Southeast Asia. As Andrew Krepinevich argued, the Army was “a superb instrument for combating the field armies of its adversaries in conventional wars but an inefficient and ineffective force for defeating insurgent guerrilla forces.”

The Army and Navy use their reserve components to hedge against unexpected demands. Thus, their reserve components do not look like the active component but are imbalanced. For example, most of the Army’s medical, transportation, engineering, civil affairs, and psychological operations units are in the reserve component.

The new Marine Corps structure might have kept some tanks, towed artillery, bridging units, military police, or logistics in the reserves as a hedge against a future war involving ground combat against a national army or a counterinsurgency campaign. However, the plan does not include such hedges.

Moving Away from Current Operations

Unacknowledged in this new Marine Corps approach, as it is across the entire department, is the tension between preparing for a conflict against a great power adversary and the need to maintain day-to-day commitments for ongoing conflicts, allied and partner engagement, and crisis response. The Trump administration, like the Obama administration before it, has chosen capability overcapacity in its strategy documents. However, the press of operational demands has been unrelenting despite the DOD’s intention to prioritize and cut back on them. This has pushed the other services—especially the Navy and Air Force—toward a high-low mix in order to cover both: advanced, and often very expensive, technologies for great power conflict and less expensive elements in relatively large numbers for less demanding threats. The Marine Corps has opted not to do this. Its smaller size will put stress on the remaining forces if deployments continue at the current level.

The Uncertain Viability of New War-fighting Concepts

The final risk is whether this new war-fighting concept of distributed operations within the adversary’s weapons engagement zone will work. The Marine Corps has sensibly conducted a lot of war-gaming and satisfied itself that the concept will succeed. However, as Marines note, the enemy gets a vote. Maintaining small and vulnerable units deep inside an adversary’s weapons engagement zone will be challenging. Even small units need a continuous resupply with fuel and munitions. If that is not possible, or if the Chinese figure out a way to hunt these units down, the concept collapses.

A Process, Not a Destination

The Force Design 2030 report emphasizes that this restructuring is not fixed and unalterable but a process where the destination is open to modification and revision. Thus, there will be a “phase III” after additional analysis and experimentation. Further changes will unfold and gaps in the current plan—for logistics, the reserves, and amphibious ships, for example—will be filled. This on-going process will also provide opportunities to reduce risk, and the Marine Corps should take advantage of that.

Mark Cancian is a senior adviser with the International Security Program at the Center for Strategic and International Studies (CSIS) in Washington, D.C.

Commentary is produced by the Center for Strategic and International Studies (CSIS), a private, tax-exempt institution focusing on international public policy issues. Its research is nonpartisan and nonproprietary. CSIS does not take specific policy positions. Accordingly, all views, positions, and conclusions expressed in this publication should be understood to be solely those of the author(s).

© 2020 by the Center for Strategic and International Studies. All rights reserved.

INFANTRYMAN'S GUIDE: Basic considerations for the defense




As the Army enters the 21st century and transforms to meet the ever- changing enemy, the antiarmor company and platoon must assume a greater role in the conduct of warfare on the modern battlefield. The antiarmor company (or platoon) contributes to success in the defense by employing long-range direct fires to destroy enemy armor and infantry forces with the TOW, M2 and MK19 fire. The antiarmor unit's mobility, heavy weaponry, and thermal observation devices define it as a key part of a larger unit's defense. The antiarmor unit can perform several missions in the defense. These missions include defend from a battle position(s) in the main battle area (MBA), participate in security operations, or serve as the reserve. The defense is a time management challenge for any unit and is continuously improved until the unit is attacked or receives a change of mission. The effectiveness of the defense depends on the efficiency of time management during planning, ISR operations, occupation, and preparation. This chapter describes the tactics and techniques used by antiarmor units in the defense and related security operations.


Military forces conduct defensive operations only until they gain sufficient strength to attack. Though the outcome of decisive combat derives from offensive actions, commanders often find that it is necessary, even advisable, to defend. Once they make this choice, they must set the conditions for the defense in a way that allows friendly forces to withstand and hold the enemy while they prepare to seize the initiative and return to the offense. A thorough understanding of the commander's intent is especially critical in defensive operations, which demand precise integration of combat, combat support, and combat service support elements.


The immediate purposes of all defensive operations are to defeat an enemy attack and gain the initiative for offensive operations. The antiarmor company (or platoon) may also conduct the defense to achieve one or more of the following purposes:

  • Gain time.
  • Retain key terrain.
  • Support other operations.
  • Preoccupy the enemy in one area while friendly forces attack him in another.
  • Erode enemy forces at a rapid rate while reinforcing friendly operations.


The characteristics of the defense—preparation, security, disruption, mass, concentration, and flexibility—are planning fundamentals for the antiarmor company (or platoon). There are two types of defensive operations: area and mobile. Traditionally, the light infantry applies the area defense pattern. Light infantry rarely applies a mobile defense pattern because it is less mobile than the enemy and lacks the ability to significantly maximize the combat power available in a single credible force. Airborne and air assault battalions and SBCTs, with the enhanced mobility of the antiarmor company, have the capability to apply area or mobile defenses. All (or a portion) of the antiarmor company can be employed as the striking force within a mobile defense. The characteristics of the defense should be considered when planning or conducting company defensive operations. (See Chapters 9 and 10 in FM 3-90 for further discussion on mobile and area defenses.) These considerations, as they apply to the antiarmor company (or platoon), are as follows:


As part of a larger element, the antiarmor company (or platoon), when augmented with additional combat support and combat service support elements, conducts defensive operations in a sequence of integrated and overlapping steps. The following paragraphs focus on the tactical considerations and procedures involved in each step. This discussion illustrates an attacking enemy that uses depth in its operations, but there will be situations where a company must defend against an enemy that does not have a doctrinal operational foundation. This requires a more flexible plan that allows for more centralized combat power rather than spreading it throughout the company's area of operations.


Security forces must protect friendly forces in the MBA and allow them to continue their defensive preparations. The enemy will attempt to discover the defensive scheme of maneuver using reconnaissance elements or attacks by forward detachments and advance guard elements. He will also attempt to breach the higher unit's tactical obstacles.


During this step, the company reconnoiters and occupies its positions. This usually includes movement from tactical assembly areas to the actual defensive sector, led by a quartering party that clears the defensive positions. The higher units establish security forces during this step, and remaining forces begin to develop engagement areas and prepare battle positions. Security is critical during the occupation to ensure the unit can avoid detection and maintain combat power for the actual defense. Soldiers at all levels 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. (See Appendix D, Firing Positions.)


As this step begins, the brigade (or SBCT) engages the enemy at long ranges using indirect fires, electronic warfare, and close air support (CAS) (deep fight). The goal is to use these assets, along with disrupting obstacles, to shape the battlefield and to slow the enemy's advance and disrupt his formations. As the enemy's main body echelon approaches the company or battalion engagement area, it may initiate indirect fires and CAS to further weaken the enemy; at the same time, the brigade's (or SBCT's) shaping operation normally shifts to second-echelon forces. Friendly forces occupy their actual defensive positions before the enemy reaches direct fire range; they may shift positions in response to enemy actions or other tactical factors.


During this step, the enemy deploys to achieve mass at a designated point, normally employing both assault and support forces. This may leave him vulnerable to the combined effects of indirect and direct fires integrated with obstacles. He may employ additional forces to fix friendly elements and prevent their repositioning. Friendly counterattack forces may be committed against the enemy flank or rear, while other friendly forces may displace to alternate, supplementary, or successive positions in support of the higher commander's scheme of maneuver. All friendly forces should be prepared for the enemy to maximize employment of combat multipliers, such as dismounted infantry operations, to create vulnerability. The enemy is also likely to set the conditions for the assault with artillery, CAS, and chemical weapons.


As the enemy's momentum is slowed or stopped, friendly forces may conduct a counterattack. The counterattack may be conducted purely for offensive purposes to seize the initiative from the enemy. In some cases, however, the purpose of the counterattack is mainly defensive, such as reestablishing a position or restoring control of the sector. The antiarmor company (or platoon) may participate in the counterattack by providing support by fire for the counterattack force or as the actual counterattack force.


The antiarmor company (or platoon) must secure its sector by repositioning forces, destroying remaining enemy elements, processing enemy prisoners of war (EPWs), and reestablishing obstacles. The unit conducts all necessary CSS functions as it prepares to continue the defense. Even when enemy forces are not actively engaging it, the unit must maintain local security at all times during consolidation and reorganization. The unit then must prepare itself for possible follow-on missions.


The BOS are a listing of critical tactical activities and provide a means of reviewing preparations or execution. The synchronization and coordination of activities within and among the various BOS are critical to the success of the antiarmor company (or platoon).


The goal of effective weapons positioning is to enable the antiarmor company (or platoon) to mass direct fires at critical points on the battlefield and to enhance its survivability. To do this, the commander (or platoon leader) must maximize the strengths of his weapons systems (TOW, M2, and MK19) while minimizing the company's exposure to enemy observation and fires. The following paragraphs focus on tactical considerations for weapons positioning.

  • The enemy situation (for example, an attack with two battalion-size enemy units may prevent the unit from disengaging).
  • Disengagement criteria.
  • Availability of indirect fires that can support disengagement by suppressing or disrupting the enemy.
  • Availability of cover and concealment and smoke to assist disengagement.
  • Obstacle integration (including situational obstacles).
  • Positioning of forces on terrain that provides an advantage to the disengaging elements (such as reverse slopes or natural obstacles).
  • Identification of displacement routes and times when disengagement or displacement will take place. Routes and times are rehearsed.
  • The size and composition of a friendly force that must be available to engage the enemy in support of the displacing unit.

While disengagement and displacement are valuable tactical tools, they can be extremely difficult to execute in the face of a rapidly moving enemy force. In fact, displacement in contact poses such great problems that the antiarmor company commander (or platoon leader) must plan for it thoroughly and rehearse displacement before the conduct of the defense. Then he must carefully evaluate the situation at the time displacement in contact becomes necessary to ensure that it is feasible and will not result in unacceptable loss of personnel or equipment.


For the indirect fire plan to be effective in the defense, the unit must plan and execute fires in a manner that achieves the intended task and purpose of each target. Indirect fires serve a variety of purposes in the defense, including the following:

  • Slow or disrupt enemy movement.
  • Prevent the enemy from executing breaching.
  • Destroy or delay enemy forces at obstacles using massed fires or pinpoint munitions.
  • Disrupt enemy support-by-fire elements.
  • Defeat attacks along infantry avenues of approach with the use of final protective fire (FPF).
  • Allow friendly elements to disengage or conduct counterattacks.
  • Use smoke to screen friendly displacement or to silhouette enemy formations, facilitating direct fire engagement.
  • Deliver scatterable mines to close lanes and gaps in obstacles, to disrupt or prevent enemy breaching operations, to disrupt enemy movement at choke points, or to separate or isolate enemy echelons.
  • Execute suppression of enemy air defense (SEAD) missions to support CAS, attack aviation, and high-payoff targets.
  • Provide illumination (if necessary).


The focus of the air defense plan is on likely air avenues of approach for enemy fixed-wing aircraft, rotary-wing aircraft, and unmanned aerial vehicle (UAV); these may or may not correspond with the enemy's ground avenues of approach. Air defense assets that are available to the antiarmor company (or platoon) are positioned based on the results of an analysis of the factors of METT-TC and the higher commander's scheme of maneuver.


Mobility focuses on preserving the freedom of maneuver of friendly forces. Countermobility limits the maneuver of enemy forces and enhances the effectiveness of fires. Survivability focuses on protecting friendly forces from the effects of enemy weapon systems.

  • Know the number of blade hours and positions (vehicle and individual) he requires.
  • Understand the number of blade hours and positions allocated to him.
  • Prepare a prioritized plan based on his analysis of "required" versus "available."

The company commander (or platoon leader) may have time to dig in only those positions that have the least amount of natural cover and concealment. Soil composition should also be a consideration in BP selection; sites to be avoided include those where the soil is overly soft, hard, wet, or rocky. However, supporting the direct fire plan must be the main consideration. It is critical that all leaders within the unit understand the following:

  • The survivability plan and priorities.
  • One leader within the company is specifically designated to enforce the plan and priorities.
  • Completion status is accurately reported and tracked.


: An air assault infantry battalion commander might specify this purpose: "We must deny the enemy access to our flank by turning the northern, first-echelon motorized rifle battalion (MRB) into our engagement area, allowing Companies B and D to mass their fires to destroy it".

Table 5-1, shows the symbology for each obstacle effect and describes the purpose and characteristics inherent in each.

Table 5-1. Obstacle effects.

Table 5-1. Obstacle effects.

Figure 5-1. Wire obstacles.

Figure 5-1.  Wire obstacles.


In addition to the CSS functions required for all operations (Chapter 11), the antiarmor company commander's (or platoon leader's) planning process should include the considerations highlighted in the following paragraphs.


The antiarmor company commander's (or platoon leader's) analysis determines the most effective control measures for every mission. This section describes the techniques and planning considerations available to the company commander (or platoon leader) as he prepares his defense.


The antiarmor company (or platoon) typically defends using one of these basic defensive techniques:

  • Defend in sector.
  • Defend from a battle position.
  • Defend on a reverse slope.

The control measures for the defense are sectors, battle positions, or a combination of these. There are no set criteria for selecting the control measures, but Table 5-2 provides some basic considerations.

Table 5-2. Selecting control measures.

Table 5-2. Selecting control measures.

Figure 5-2.   SBCT antiarmor company defense in sector, with a platoon in a battle position.

Figure 5-2.  SBCT antiarmor company defense in sector,
with a platoon in a battle position.

Figure 5-3. Alternate position.

Figure 5-3.  Alternate position.

  1. A supplementary position is to the flank or the rear of the primary position. It allows the unit to defend against an attack on an avenue of approach not covered by the primary position (Figure 5-4). It can be assigned when the unit must cover more than one avenue of approach. A unit moves from its primary, alternate, or supplementary position only with the higher commander's approval or when a condition exists that the higher commander has prescribed as a reason to move.

Figure 5-4. Supplementary position.

Figure 5-4.  Supplementary position.

Figure 5-5. SBCT antiarmor company defense from mutually supporting battle positions.

Figure 5-5.  SBCT antiarmor company defense from mutually supporting battle positions.

Figure 5-6. Multiple engagement areas.

Figure 5-6.  Multiple engagement areas.

c.   Defend on a Reverse Slope. An alternative to defending on the forward slope of a hill or a ridge is to defend on a reverse slope. Figure 5-7, depicts an airborne antiarmor company with two infantry platoons in a reverse slope defense. In such a defense, the company (or platoon) is deployed on terrain that is masked from enemy direct fire and ground observation by the crest of a hill. Although some units and weapons may be positioned on the forward slope, the crest, or the counterslope (a forward slope of a hill to the rear of a reverse slope), most forces are on the reverse slope. The key to this defense is control of the crest by direct fire.

Figure 5-7. Airborne antiarmor company defense on a reverse slope.

Figure 5-7.  Airborne antiarmor company defense on a reverse slope.

  • The forward slope has little cover and concealment.
  • The forward slope is untenable because of enemy fire.
  • The forward slope has been lost or not yet gained.
  • There are better fields of fire on the reverse slope.
  • It adds to the surprise and deception.
  • The enemy has more long-range weapons than the defender.


The antiarmor company (or platoon) may participate in a defense by operating as a battalion's security force (or part of the security force) and as a battalion's reserve. The SBCT antiarmor company may have a slight variation of these two employment options.

  • Block a penetration from an attack by fire position.
  • Occupy a battle position.
  • Reinforce another unit's position.
  • Destroy enemy CS or CSS forces.

The reserve is normally positioned in an assembly area to wait for orders to execute one of several contingencies. The antiarmor company commander (or platoon leader) conducts rehearsals of all his contingency missions. During security operations, he receives the priority of the potential missions to ensure he can rehearse them with his subordinate leaders. Another technique for the company is to have the company XO, with the platoon sergeants, rehearse the potential missions while the company is conducting the security operation. Full-up rehearsals may not be possible.


The engagement area is where the company commander (or platoon leader) intends to destroy an enemy force using the massed fires of all available weapons. The success of any engagement depends on how effectively he can integrate the obstacle plan, the indirect fire plan, the direct fire plan, and the terrain within the engagement area to achieve the unit's tactical purpose. Beginning with evaluation of METT-TC factors, the development process covers these steps:

  • Identify all likely enemy avenues of approach.
  • Determine likely enemy schemes of maneuver.
  • Determine where to kill the enemy.
  • Emplace weapons systems.
  • Plan and integrate obstacles.
  • Plan and integrate indirect fires.
  • Rehearse the execution of operations in the engagement area.

The following paragraphs outline planning and preparation procedures an antiarmor company commander may use for each of these steps.

Figure 5-8. Identify all likely enemy avenues of approach.

Figure 5-8.  Identify all likely enemy avenues of approach.

Figure 5-9. Determine the enemy's scheme of maneuver.

Figure 5-9.  Determine the enemy's scheme of maneuver.

Figure 5-10. Determine where to kill the enemy.

Figure 5-10.  Determine where to kill the enemy.


In marking TRPs, use thermal sights to ensure visibility at the appropriate range under varying conditions, including daylight and limited visibility (darkness, smoke, dust, or other obscurants).

Figure 5-11. Emplace weapons systems.

Figure 5-11.  Emplace weapons systems.

Figure 5-12. Plan and Integrate obstacles.

Figure 5-12.  Plan and Integrate obstacles.

Figure 5-13. Integrate direct and indirect fires.

Figure 5-13.  Integrate direct and indirect fires.

  • Rearward passage of security forces (as required).
  • Closure of lanes (as required).
  • Movement from the hide position to the battle position.
  • Use of fire commands, triggers, and maximum engagement lines (MELs) to initiate direct and indirect fires.
  • Shifting of fires to refocus and redistribute fire effects.
  • Emplacement of scatterable mine system.
  • Preparation and transmission of critical reports (FM or FBCB2 )
  • Assessment of the effects of enemy weapons systems.
  • Displacement to alternate, supplementary, or successive battle positions.
  • Cross-leveling or resupply of Class V.
  • Evacuation of casualties.


The company commander should coordinate the rehearsal with the higher headquarters to ensure other units' rehearsals are not planned for the same time or location. Coordination leads to more efficient use of planning and preparation time for all units. It also eliminates the danger of misidentification of friendly forces in the rehearsal area, which could result in fratricide.


This is a set method of controlling the preparation and conduct of a defense. SOP should describe priority of work to include individual duties. A commander changes priorities based on the situation. The leaders in the unit all should have a specific priority of work for their duty position.

  • Post security (air guards, observation posts, patrols, chemical agent alarms, assign observation sectors to scan).
  • Plan and emplace direct fire control measures, TRPs (all visual spectra), trigger lines
  • Plan indirect fires and ensure their effects do not obstruct the gunner's view of the engagement area.
  • Prepare primary positions; leaders prioritize their subordinate units for engineer digging assets


Marking positions during the leader's reconnaissance allows digging to occur prior to the entire unit occupying the position.

  • Select and prepare alternate positions. If engineer assets do not have the blade time to dig positions, give careful consideration to existing cover.
  • Designate supplementary positions. These positions may not be allocated engineer effort, so the same guidance provided for alternate positions applies.
  • Designate hide positions. These are positioned where they are concealed from enemy reconnaissance assets and preferably safe from the impact of artillery fires on primary positions.
  • Dig primary fighting positions for anticipated fighting conditions (daylight or limited visibility). Supervision of engineer assets is invaluable to ensure positions are dug to standard and to maximize the precious available time.
  • Achieve mutual support or concentration of fires.
  • Coordinate with adjacent units to ensure dead space does not exist.
  • Emplace tactical obstacles.
  • Clear fields of fire.
  • Establish coordination or contact points.
  • Emplace protective obstacles.
  • Emplace wire for communications.
  • Preposition (cache) and dig in ammunition.
  • Prepare range cards or platoon and company defensive sector sketches.
  • Mark and prepare routes.
  • Rehearse movement from hide into the position.
  • Rehearse casualty evacuation.
  • Rehearse actions during limited visibility.
  • Use briefbacks to ensure the mission is understood.


Antiarmor leaders prepare sector sketches based on their defensive plan. These sector sketches are based on range cards prepared for all crew-served weapons systems (TOW, M2, and MK19) and individual weapons. The sector sketch allows the higher headquarters to determine the effectiveness of the direct fire plan. If necessary, the higher commander makes adjustments to the sectors and or position of his subordinates. Sector sketches also are useful for units occupying previously prepared defenses (relief in place).

  • Prominent terrain features in the sector of fire and the ranges to them.
  • Each antiarmor squad's primary and secondary sectors of fire.
  • MELs.
  • TRPs.
  • Dead space.
  • Phase lines (triggers) where firing should begin or where the section is to disengage.
  • Obstacles and indirect-fire targets.
  • Distance and direction to all dead space and TRPs.

Table 5-3. Platoon engagement matrix.

Table 5-3. Platoon engagement matrix.


The ultimate goal of adjacent unit coordination is to ensure unity of effort in the accomplishment of the battalion and brigade (or SBCT) mission. Items that adjacent units must coordinate include, but are not limited to, the following:

  • Unit positions, including locations of command and control nodes.
  • Locations of observation posts and patrols.
  • Overlapping fires (to ensure that direct fire responsibility is clearly defined).
  • Target reference points.
  • Primary, alternate, and supplementary battle positions.
  • Indirect fire and automated net control device (ANCD) information.
  • Obstacles (location, orientation, and type).
  • Air defense considerations, if applicable.
  • Routes to be used during occupation and repositioning.
  • CSS considerations.


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Defensive operations usmc


Chapter 8

Defensive Operations

Little minds try to defend everything at once, but sensible people look at the main point only; they parry the worst blows and stand a little hurt if thereby they avoid a greater one. If you try to hold everything, you hold nothing.
Frederick the Great











 Figure 8-1.  The Mobile Defense

Figure 8-1. The Mobile Defense

A striking force is a committed force organized to conduct the decisive attack in a mobile defense. It normally comprises the maximum combat power available to the commander at the time of the attack.


 Figure 8-2. Area Defense

Figure 8-2. Area Defense





Risk in Retrograde


 Figure 8-3.  Operational Framework in the Defense

Figure 8-3. Operational Framework in the Defense


Decisive Defensive Operations—Pusan, Korea

By the end of August 1950, the North Korean People's Army (NKPA) occupied most of the Republic of Korea (ROK), less the Pusan pocket on the southeast portion of the peninsula. President Kim Il Sung was amazed at the speed with which the NKPA had moved south, and he assembled 98,000 more troops to crush the Eighth Army. Precariously held, the Pusan pocket contained about 120,000 US and ROK soldiers. The operation became hundreds of large and small engagements marked by thousands of casualties.

The NKPA struck at numerous points along the perimeter, expending men and resources in an effort to create a penetration. But the line held and fresh United Nations (UN) forces arrived to bolster the defense. Sensing that an opportunity was slipping away, the NKPA attacked with increased intensity on 31 August 1950. Despite tremendous punishment by UN air force bombing and strafing, the North Koreans breached the defensive lines in several areas. The 24th Infantry Division counterattacked, while the 1st Cavalry Division and the 1st ROK Division held at Taegu. Two enemy divisions struck the 25th Infantry Division in a bloody fight that saw Sobuk Ridge change hands 13 times in less than a month. The line held despite US units giving ground or fighting in isolation. While the NKPA made impressive gains along the perimeter, the defense held and the ports remained open.

The defense of the Pusan perimeter proved decisive in that it broke the North Korean will to continue the attack and fixed remaining enemy forces. Further north, US forces executed Operation Chromite at Inchon, a turning movement that trapped the NKPA, threatened it with imminent destruction, and allowed UN forces in the Pusan pocket to break out and resume offensive operations.


Shaping Defensive Operations—2d SANG Brigade at Khafji

Defensive operations often have significant political implications. During the evening of 29 January 1991, the Iraqi 5th Mechanized Division launched several large probes across the Saudi Arabian border. Elements of the 2d Saudi Arabian National Guard (SANG) Brigade—a force accompanied by American advisors and a Marine air/naval gunfire liaison company—met them at the town of Khafji, Saudi Arabia. The Iraqis seized the town, cutting off two Marine reconnaissance teams, who evaded capture while continuing to call in air and field artillery support. The next day, the 2d SANG Brigade attempted to retake Khafji without success. However, on 31 January, the brigade attacked again, and by 1 February succeeded in clearing Iraqi resistance.

This relatively small tactical action was important because it convinced the theater commander that the Iraqis could not conduct complex operations and were vulnerable to air interdiction. This information helped to shape future coalition operations. The action, by demonstrating that the Saudi forces would fight aggressively, strengthened the coalition and bolstered its will. Lastly, the operation demonstrated that US and coalition forces could conduct successful multinational operations, a discovery with strategic implications.







Terrain and Weather

Troops and Support Available

Time Available

Civil Considerations



Battle Command

Operations in Depth

Enemy Penetrations

Encirclements and Breakouts

Protecting Sustaining Operations

Weapons of Mass Destruction


Terminating the Defense




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Offensive and Defensive Operations – Supersquad 2020

The sisters climbed naked through the university until they found an audience. Oh, and here are my volunteers, - said Vita when the naked sisters entered the audience. - Stand beside. On my volunteers, you can clearly trace the girl's changes during pregnancy. Tanya and Luda stood face-to-face to the audience.

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She nodded her head, looking fearfully into my eyes. Animal horror emanated from her. I again went behind her and ran my hand along the spine, feeling with pleasure the soft resistance of the elastic muscles. Then he swung it and to begin with, lightly slapped her on the back above the waist.

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