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by SFC Stephen W. Bell

"I approve of all methods of attacking provided they are directed at the point where the enemy's Army is weakest and where the terrain favors them least."

--Frederick the Great

A true statement, then and now. The challenge faced through the years by engineers is how to visualize where the enemy's weak point is.

I am sure everyone has heard of the process called Intelligence Preparation of the Battlefield (IPB). The IPB is a process the Army uses to find the enemy's weak point. But did you also know that the engineer is the primary proponent for the terrain portion of the IPB process? Doctrinal references such as FM 34-130, Intelligence Preparation of the Battlefield, and FM 5-33, Terrain Analysis, systematically spell out how to define the effects of terrain on our forces and the enemy. When terrain analysis is done properly, the commander and battle staff have key and decisive terrain identified that often defines the parameters of mission success.

According to FM 34-130, when evaluating the terrain's effects on combined arms operations, the analyst should:

  • Analyze the defensible terrain within each avenue of approach (AA) to determine locations where obstacles can be used.

  • Further identify where the terrain allows breaching operations at each location. This includes concealed and covered routes towards the breach site and terrain that supports suppressing fire during the breaching operation.

  • Analyze streams and rivers within the area of operations (AO). Focus on bridges, ford sites, and areas that support river-crossing operations.

  • Identify other man-made or natural obstacles within the AO, such as railroad tracks with steep embankments. Identify the effect of each obstacle upon the movement of different type units. Further analyze the locations where these obstacles can be easily traversed or crossed.

While all Battlefield Operating Systems (BOS) within combined arms are capable of terrain analysis, the engineer has the unique responsibility of showing the impact of terrain on friendly forces maneuver. For example, while an armor task force commander may use Terrabase to find positions for retransmission, he might not consider the terrain's effects on the direct fire planning for an attack. The engineer should understand and brief the terrain's effects during the mission analysis briefing. The engineer, at a minimum, should address the following.


The common acronym used for the military aspects of terrain is "OCOKA." This is a very logical sequence to use as a briefing format.

O - Observation and fields of fire. This should cover the types of weapons systems to be employed, for both friendly and enemy forces, and their maximum ranges.

Example statements:

  • "Sir, I believe the enemy will prefer to attack in the north. This assumption is based on the broken rolling wadi systems and the intervisibility (IV) lines in the area. Since he is fighting from unstabilized weapons platforms, this will allow him to set and echelon his firing lines."

  • "After our lead elements move through this pass we lose communications with them."

Another example is from a seminar held at the Rand Arroyo Center in Washington, DC. This seminar covered Russian lessons learned from the Battle of Grozny that draws special attention to the dynamics of the urban warfare environment:

"They found that boundaries between units were still tactical weak points, but that it wasn't just horizontal boundaries they had to worry about. In some cases, the Chechens held the third floor and above, while the Russians held the first two floors and sometimes the roof. If a unit holding the second floor evacuated parts of it without telling the unit on the ground floor, the Chechens would move troops in and attack the ground floor unit through the ceiling. Often this resulted in fratricide as the ground floor unit responded with uncontrolled fire through all of the ceilings, including the ones below that section of the building still occupied by Russians. Entire battles were fought through floors, ceilings, and walls without visual contact."

C - Cover and concealment. This should address natural vegetation that can conceal friendly forces or enemy forces from observation. It should also encompass natural cover that will inhibit the use of direct and indirect fire weapons systems. These might be key factors in selecting the terrain to set an attack position or the insertion route for a scout section.

O - Obstacles. This is a subject near and dear to every engineer's heart. But sometimes engineers get so focused on the man-made obstacles that they do not consider the many other battlefield conditions that prevent units from moving about freely.

  • The political situation may influence movement. A good example of this was in Panama during preparations for Operation JUST CAUSE. Due to the standing treaties with that country, U.S. forces were limited at times to where, and in what posture, they could move.

  • Certain religious or sacred areas may restrict movement. Units clearly cannot set a battle position (BP) on top of a cemetery.

  • The natural hydrology of an area may restrict or limit trafficability at certain times throughout the year. The rice fields of Korea are an example. In the winter when they are frozen, they will support almost any vehicle, but in the growing season they may only be maneuverable by dismounts.

  • Displaced civilians creating obstacles on the battlefield is another problem. This proved to be a key obstacle for the British Army in Belgium during the Second World War.

  • Throughout the campaigns in Vietnam and South West Asia, unexploded ordnance (UXO) and dud- producing munitions increasingly restricted freedom of maneuver. On today's battlefield, air and artillery- delivered improved conventional munitions (ICMs) and scatterable mines have a significantly high dud rate. As sub-munitions and scatterable mine technology becomes more complex, entire areas may be restricted to ground maneuver.

K - Key terrain. These can be man-made or natural areas. Bridges, choke points, high ground, or military installations such as airfields are some examples. Lines of communication and main supply routes (MSRs) are often critical to the success or failure of an operation. These should be highlighted in detail during the mission analysis briefing. Use of local names and characteristics can sometimes make it easier for everyone to keep a common picture, but an 8-digit grid coordinate is far less confusing during the heat of battle.

A - Avenues of approach. FM 34-130, Appendix B, contains tables that can help visualize how large a force a given mobility corridor can support. This information can help a unit understand what size force the enemy can bring to bear against it. This can also aid engineers with predictive analysis on the speed of enemy forces. Engineers must also look at possible drop zones and landing zones that support friendly and enemy operations.


Engineers often wait too long to start their terrain analysis process. Engineers should be able to start amassing information and developing terrain products as soon as they find out what the AO and area of interest (AI) will be. Units often arrive at the National Training Center (NTC) believing they will have time to build terrain products during the Reception, Staging, Onward Movement and Integration (RSOI) phase of the rotation. Not so. The process must start prior to deployment. After arriving in a theater of operations, the unit will only have time to refine what they have done prior to deployment.

All too often, a battalion headquarters arrives at NTC with very good, detailed terrain analysis products, but their companies will not have any of this information. Higher headquarters has access to more resources and expertise and must push that information to subordinates to make them successful. A task force (TF) engineer should have the same common picture as the brigade engineer.

The engineer battalion headquarters and the assistant brigade engineer (ABE) must assist the TF engineers. All terrain products and analyses, situational templates, and any other products should be provided using overlays and computer disks. This reduces the TF engineer's requirement to replicate this work and allows him time to focus on the other aspects of mission analysis. Using the task force liaison officer (TF LNO) is a great way to make this happen.

Surface Configuration Overlay

This overlay is very time consuming and may require the assistance of a terrain team, but it is a great basis from which to produce many of the other products. By using the process described in FM 5-33, the effects of slope, drainage, and other restrictions can be determined.

Vegetation Overlay

This is also a very time-consuming process. The advantage of having this product as a reference, however, is the ability to understand the effects of concealment on the battlefield. It can assist the staff in determining the best locations to place assembly areas, attack positions, and battle positions. The S2 can use it when doing reconnaissance planning by looking at how the enemy can also use these same resources.

Cross-Country Mobility Overlay (CCM)

The CCM has been referred to as an avenue-of-approach overlay or a time-distance overlay. It is a great tool to help the staff understand the speed at which equipment can be moved around the battlefield. When this is compared with the named areas of interest (NAIs) developed by the S2, effective enemy event triggers for things such as artillery-delivered FASCAM or Volcano minefield employment can be developed.

Combined Obstacle Overlay (COO) and Modified Combined Obstacle Overlay (MCOO)

After the surface configuration overlay, vegetation overlay, and CCM are completed, the MCOO is a method for putting that information into a single workable format. It allows the UNRESTRICTED, RESTRICTED, and SEVERLY RESTRICTED terrain to be viewed along with any other key information the commander or staff may deem necessary. Examples are bridges, fords, built-up areas, key terrain, and lines of communication. The MCOO can assist in friendly obstacle planning by allowing the staff to integrate the obstacle plan with the terrain.

Line-Of-Sight (LOS) Analysis

This is probably one of the least used and most useful tools in terrain analysis. There are several different programs available, but the most easily accessible is Terrabase II. This program works off digital terrain elevation data (DTED), the standard elevation data for military mapping. The different DTED datums for any area that is currently mapped by DOD are available through the map supply system. The program CD-ROM comes with several DTEDs for military training areas built in. DTED level one is probably the preferred level for most units because their entire AO and AI can be loaded onto a standard IBM-compatible computer. The Terrabase II program is so versatile, it should be loaded on at least one computer in every unit. Possible uses include, but are not limited to, the following examples:

  • A unit master gunner can do direct fire planning on proposed battle positions (BPs).

  • The S2 can take confirmed enemy positions and look for covered and concealed axes of attack through their defenses.

  • Engineer headquarters can confirm that their subordinate unit obstacles are tied into the maneuver unit's direct fire plan.

  • The signal officer can do retransmission position planning to ensure line-of-sight communications.

  • The fire support officer and reconnaissance planners can ensure that proposed team locations actually support the maneuver plan.

  • As key terrain is identified prior to deployment, the S2 and S3 sections of the engineer battalion can build a LOS reference book. Printing this LOS information on transparencies provides a quick reference to a given area.


We must train engineer staff officers and NCOs on the IPB process and ensure they understand its importance to the combined arms fight. If engineers do the necessary preparation, they can have a dramatic effect on shaping the battlefield. As engineers reduce the size of units and their staffs, it is critical that they remember whom it is they are supporting. Division and brigade staffs do not win battles, but they can assist in losing them by not supporting their maneuver task forces. We must ensure that IPB products get to the fighting task forces.


1. FM 34-130 --
2. FM 5-33 --
3. DTED --
4. USGS --
5. Engineer Center Homepage --
6. Terrabase II --, DSN 676-4119 or (573) 563-4119 Mr. Larry Helms or Mr. Steven Stacy.

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