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Chapter 6

Reserve Obstacles

This chapter implements STANAG 2017.

This chapter outlines the procedures to plan, prepare, and execute reserve obstacle groups. Reserve obstacle groups are those for which the commander restricts execution authority. These are "on-order" obstacles. The commander specifies the unit responsible for obstacle emplacement, guarding, and execution. Units normally plan and prepare reserve obstacles during preparation of the battlefield. Units execute them only on command of the authorizing commander or based on specific criteria that the commander identifies. The purpose of a reserve obstacle group is to retain control over the mobility along an AA. Commanders use reserve obstacles when failure to maintain control over the mobility along an AA will have disastrous effects on the current battle or future operations.


Commanders carefully select and have their staffs plan reserve obstacles. Normally, the commanders assign a maneuver unit as a guard element to protect the reserve obstacle site. They also commit an engineer unit to provide the technical expertise to ensure that the obstacle is executed. Both the maneuver and engineer units that the commander dedicates to the reserve obstacle have other potential missions. The commander must conclude that the reserve obstacle group is so critical that the loss of units to protect and execute the obstacle outweighs the combat potential of those units in other areas.

The commander must clearly identify the criteria for executing the obstacle. Reserve obstacles require detailed coordination and synchronization to ensure success.

Units normally install, but do not execute, reserve obstacles early in the preparation phase because they are a critical part of the plan. Units may use a reserve obstacle to close a lane in a larger obstacle. Obstacles used for rapid lane closure are often demolition obstacles or mines; however, the type of obstacle used is only limited by imagination and ingenuity.


Key persons involved in the execution of a reserve obstacle (see Figure 6-1) are the--

  • Authorizing commander.

  • Guard commander.

  • Firing commander.

Figure 6-1. Reserve-obstacle responsibilities.


The authorizing commander is the maneuver commander who determines the requirement for a reserve obstacle. The authorizing commander--

  • Establishes the criteria and procedures for executing the obstacle. Typically, he withholds authority to execute until he gives the order, using specific code words.

  • Selects the code words for the execution of the obstacle.

  • Establishes other specific criteria for executing the obstacle if he does not withhold the execution authority. He may authorize the guard commander to execute the target based on his own initiative or based on other criteria.

  • Determines the need for a separate guard force. If a small guard force can protect the obstacle site, he may choose to combine the duties of the guard force and the firing party. In this case, the guard commander and the firing commander are the same person.

  • Determines the need for a separate firing party. If the reserve obstacle requires an engineer technical expert on site to ensure obstacle execution, then the firing party is separate from the guard force.


The guard commander is the leader of the unit that protects the obstacle. He is a commissioned officer or an NCO. The guard commander--

  • Ensures that the obstacle site is not captured by the enemy.

  • Gives the firing commander the order to execute the obstacle (based on the criteria that the authorizing commander established).


The firing commander is the leader of the firing party and is an engineer NCO, unless the commander determines that there is no need for an engineer technical expert on site. The firing commander--

  • Executes the obstacle when the guard commander orders him to do so.

  • Inspects and repairs the obstacle, as required.

The specific orders to the guard and firing commanders are shown on the sample STANAG Form 2017 (see Figure 6-2).


The staff plans reserve obstacles during the decision-making process. The following paragraphs contain some considerations for determining the requirement for, and the planning, preparation, and execution of, reserve obstacles.

The commander determines the requirement for a reserve obstacle during the COA analysis or possibly following the COA development. The commander may also receive a requirement for a reserve obstacle from a higher commander as a specified task. If so, the staff identifies the requirement during the mission analysis.

If the commander decides that he needs to retain control over mobility along an AA, he has two options. He can--

  • Assign a specified task to a subordinate unit to maintain a lane.

  • Use a reserve obstacle.

The commander must consider the effect of the premature loss of mobility along an AA. For example, if an ACR is withdrawing under pressure through a division sector, premature loss of mobility along the AA may slow or even stop the ACR's withdrawal. The corps commander may specifically task the division commander to ensure that the ACR's withdrawal lanes are clear until the ACR has withdrawn. Thus he allows the division commander to determine the need for reserve obstacles. The corps commander may also decide to use reserve obstacles (see Figure 6-3).

If the commander decides to use reserve obstacles, he again has two options. If specific obstacle sites are obvious, such as bridges across a major river, the corps commander may designate those sites as corps reserve obstacles. This will require detailed planning by the corps staff and coordination down to the executing unit. If obstacle sites are not obvious, the corps commander may specify that any obstacles along the withdrawal lanes are corps reserve targets. This will require subordinate units to conduct detailed planning and then coordinate through operational and engineer channels with the corps.

Figure 6-2. Sample demolition order.

Figure 6-2. Sample demolition order (continued).

Figure 6-3. Considerations for using a reserve obstacle.

The need for reserve obstacles is not limited to ensuring successful rearward passage of friendly units. The reserve obstacle may control key terrain along a CATK axis that is along the most dangerous enemy AA (see Figure 6-4). Control of the key terrain (a choke point) along the CATK axis may be critical to success in the battle. The commander may reserve the obstacle controlling the key terrain to retain his flexibility to commit the CATK force along the axis and have a means to close the AA if the enemy uses the most dangerous AA.

Figure 6-4. Using a reserve obstacle to control key terrain.


Once the commander decides on the need for a reserve obstacle, the staff examines the SITEMP. It is used to determine the--

  • Size of the guard force required.

  • Requirement to secure the obstacle, either by fire or occupation.

  • Size of the obstacle required.

  • Most effective type of obstacle.

The expected threat determines the size of the guard force. The enemy and terrain situation dictate whether the guard force must secure the site by occupation or whether they can do so from a distance by fire. The terrain that determines the size of the AA may determine the size of the obstacle. The enemy's breaching capability may determine the most feasible obstacle. For example, if the enemy does not have organic assault bridging, then tank ditches and RCs may be the best obstacle.


The staff analyzes the COA to determine the--

  • Location of the obstacle relative to subordinate units' positions.

  • Ability of the unit to cover the reserve obstacle group by fire following execution.

  • Most likely subordinate unit to assign to the guard force mission.

The best spot for an obstacle may not be the best spot to bring overwhelming combat power to bear. When the unit uses the reserve obstacle to close a lane in a properly planned directed obstacle, the reserve obstacle is already integrated with fires. However, in some cases, a reserve obstacle site is dictated by a higher commander or the terrain. A reserve obstacle directed by the higher HQ may require the subordinate unit to adjust its positions to cover the obstacle by fire. In some terrain, there may be only a few sites where a commander can use reserve obstacles to control mobility along an AA. This terrain is usually dominated by some type of existing obstacle (such as a river, canal, or canyon). If the commander decides to use a reserve obstacle, he repositions forces to ensure that the obstacle is covered by fire.


The staff places the reserve obstacle group relative to the terrain and friendly maneuver graphics to support the COA. Normally, the desired obstacle effect of a reserve obstacle is to block. Even if it is used to close a lane in a directed fix obstacle group, the commander uses the reserve obstacle to block the AA, in this case the lane; however, the commander may use reserve obstacles to achieve any of the four obstacle effects. The staff indicates the location of reserve obstacles by using the obstacle effect graphics and annotating them as reserve obstacles.


Reserve obstacles are high-priority obstacles. Because a reserve obstacle is critical to the plan, units must emplace reserve obstacles early in the preparation phase.


The commander's decision to use reserve obstacles is based on--

  • Analysis of the COA.

  • Detection of mobility requirements.

An additional consideration is the establishment of procedures for traffic control and lane marking. Figure 6-5 shows a possible lane-marking system based on lane-marking guidance from FM 90-13-1.

After the commander decides on a COA, the staff can do the detailed planning for reserve obstacles. This detailed planning involves designing and resourcing the reserve obstacle group.

Figure 6-5. Lane marking.


The staff determines--

  • What obstacle assets are available.

  • Which type of obstacle asset is best to use.

The staff must know the obstacle emplacement assets that are available. It finds this information by reexamining the facts and assumptions for the mission. The staff limits its consideration of available assets to those that are quickly executed. Demolition obstacles, preconstructed obstacles (like the falling blocks used in Korea), and SCATMINEs are examples of easily executed obstacles. For small lanes, hand-emplaced conventional mines may be suitable. If the commander decides to use SCATMINEs, the staff ensures that the asset directed to emplace the reserve obstacle is available for the mission at the required time. The obstacle emplacement unit is dedicated to the reserve obstacle, which makes it an "on-order" mission. The staff identifies potential situations where SCATMINE assets may not be available and ensures that the commander understands any risk associated with their nonavailability.


The staff prepares orders and provides information on reserve obstacles on the scheme-of-obstacles overlay, in a reserve-obstacle-execution matrix, and in a demolition order for the unit with the guard force mission.


Reserve obstacles are included on the scheme-of-obstacles overlay. The staff uses the obstacle effects graphics and, in many cases, the individual obstacle symbols (if the commander intends to use a specific type of individual obstacle for the reserve obstacle). This provides the emplacing unit with clear guidance on what obstacle effect is desired and what individual obstacles to use.


The obstacle-execution matrix for reserve obstacle groups is similar to the matrix for directed obstacles (see Figure 6-6, ). Typical information shown on the matrix includes--

  • Zone/belt/group designation and individual obstacle numbers.

  • Location, effect, and priority of the group.

  • Emplacing and owning units.

  • Designation of the firing and guard commanders.

  • Emplacing asset and asset location.

  • Any special instructions for each group.

Figure 6-6. Reserve-obstacle-execution matrix.


The demolition order, STANAG Form 2017, consists of a single sheet printed on both sides. This order can be used for any obstacle, not just demolitions. Figure 6-2, includes an example of a completed demolition order.

The demolition order may include emergency firing orders (indicated on STANAG Form 2017, items 5 and 6). The commander performs a risk assessment on the execution criteria. The commander has two options: withhold execution authority or grant execution authority to the guard commander based on--

  • The possibility that the enemy is about to capture the obstacle.

  • A NLT time being reached.

  • Specific friendly action.

  • Specific enemy action.

  • The combination of an enemy and a friendly action.

If the commander does not establish emergency firing orders, he takes the risk of the enemy destroying the guard unit and the obstacle not being executed. If he establishes emergency firing orders, he takes the risk that the premature execution of the obstacle may hamper future operations. The commander makes a decision on execution criteria and issues clear orders concerning the authority to execute the obstacle (see Figure 6-7).

Figure 6-7. Emergency fire-order criteria.


Once the order is published, the next step is to rehearse the execution of the obstacle. Reserve obstacles require detailed coordination and execution. The focus of the rehearsal is to confirm the timing requirements. Units should conduct this rehearsal as part of a larger rehearsal with minimal simulation. The following timing requirements are considered during the rehearsal (see Figure 6-8):

  • Time required for the guard commander to notify the firing commander to execute the target.

  • Time required to execute the target.

  • SCATMINE arming and duration time, if applicable.

The guard force and the firing party rehearse notification procedures, using redundant communication procedures, such as wire and radio. They rehearse the time required to receive notification and move to the firing point under all conditions.

The firing commander and the guard commander calculate how long it will take to execute the obstacle. The full rehearsal includes rehearsal of the backup plan and considerations for execution in reduced visibility, such as smoke, darkness, or fog. Once these times are determined through rehearsal, the firing commander informs the guard commander.

Figure 6-8. Minimum timing requirements for reserve obstacles.

Another time consideration is the arming and duration times. If SCATMINEs are used, the arming and duration times can be a significant factor. For example, it takes two minutes for a MOPMS dispensed mine to arm. The duration on MOPMS is sixteen hours (assuming the mines are recycled three times) from the time the mines are armed; however, the mines begin to SD at 80 percent of their expected life. It is important not to execute this and similar systems too late or too early.

During the rehearsal, the guard commander also identifies the decision point for executing the obstacle according to emergency firing orders. Emergency firing orders may not require a physical DP but may require execution of the obstacle based on enemy or friendly actions that the guard commander cannot see. If so, the guard commander confirms, with the authorizing commander, how he will get the information that drives the decision to execute the obstacle (such as a report from the TF scouts that the enemy has reached a certain location).

If execution depends on imminent enemy capture of the obstacle site, the guard commander makes assumptions about how much combat power he must have to retain control of the site. He must also consider the time requirements for execution that will affect the DP. For example, he must determine at what point during the fight to retain control that he can order execution and still have enough time for notification, execution, and arming.

If execution is based on a certain size enemy force reaching the obstacle site, the guard commander uses the time required for obstacle execution and works backwards to locate the DP to execute the obstacle. Ideally, the point should be clearly marked with a TRP. This spot may change based on visibility conditions.

If the reserve obstacle is also a lane, the coordination required is similar to the coordination required to conduct a passage of lines. The guard commander must know the following:

  • The number of vehicles to expect.

  • The near and far recognition signals.

  • The passage time.

Another important element to consider during the rehearsal is the commitment of assets, especially if the assets have other missions. For example, artillery assets must be available to fire a reserve ADAM/RAAM obstacle. During the rehearsal, the staff verifies the availability of the asset and identifies additional situations where the asset may not be available. It ensures that the executing unit understands the commander's priorities.

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