In the last entry we identified three categories of obstacles (natural, man-improved, and manmade). In this entry we’re going to look at natural obstacles and try to gain an understanding of why they work and how they impact a threat force. Remember a natural obstacle is any feature already found existing in the environment that will frustrate, channel, delay, or otherwise impede a threats movement (our obstacle goals). Natural obstacles include bodies of water, terrain features (such as cliffs, steep draws and jagged spurs, and depressions), thickly forested areas, and any kind of terrain that makes crossing it a slow-go/no-go effort. By slow-go we mean it will severely degrade the movement rate and capabilities of a threat. No-go means that the terrain is impassible which typically only applies to vehicles but can apply to dismounts that are not properly equipped to deal with it (i.e. a cliff).
Some quick definitions here. In these entries when I use the phrase “fight through” obstacles what I mean here is “Breach”. When the threat breaches and obstacle they are creating a path through the obstacle whether under fire or not. The phrase “command and control” (aka C2) means the process by which a threat directs its assets (troops, vehicles, weapons, and other capabilities) during movement and an assault.
Why do natural obstacles work? They present an established movement challenge to the threat to maintain momentum, direction, and command and control. The key thing I want you to gain from this entry is a basic understanding of what a natural obstacle is, why it’s an obstacle, and how it impacts the threat. These points are going to be crucial when we discuss man-improved and manmade obstacles.
When we talk about threat momentum we’re referring to the speed at which the threat wants to advance or assault either by vehicle or on foot. Natural obstacles frustrate and disrupt the threats momentum by forcing them to either bypass around or fight through to maintain their advance. Unless the threat has taken into account that bypass or breach it’s going to cost the threat more time and effort in both instances. Note I stated unless the threat has taken it into account. When developing a plan of attack a competent threat that has conducted at least a rudimentary terrain analysis will take into account the amount of time required to deal with a natural obstacle. Most often with natural obstacles fighting through them just isn’t feasible especially when it comes to vehicles. That coupled with the amount of time the threat believes it will take to bypass or fight through a natural obstacle will greatly impact their decision making process when it comes to planning the direction of movement both during preparation and execution of an assault.
How can an obstacle prevent a threat from maintaining direction? If the natural obstacle is greater than the threats capability to traverse it then it’s going to force the threat to reroute. This is less true for dismounted (on foot) forces than vehicles. Additionally regaining the direction of travel after bypassing an obstacle takes time and effort. Threat forces have to reconsolidate (regroup) and re-establish command and control prior to proceeding. Some examples of how a natural obstacles frustrates direction of movement are if dismounted troops aren’t equipped to scale cliffs or cross rivers then they are most likely going to have to bypass them. Likewise if say a river or deep creek exceeds the fording capability of the threats vehicles then they won’t be able to cross at those locations. FYI: most military vehicles are designed to climb at maximum a 60 degree solid slope – a very common design parameter. Anything steeper and that vehicle either won’t be able to overcome its own weight and maintain traction or risks flipping. Trails along the sides of hills that exceed 30 to 40 degrees (once again a common design parameter) are extremely difficult for both wheeled and tracked vehicles to traverse. Below is a tabulated list of common military vehicle performance data (taken from TMs).
How do natural obstacles impact the threats ability to maintain command and control? By presenting dense constricted terrain it’s going to be more difficult for the threat to maintain awareness of where his assets are and to control those assets movement in a disciplined manner unless they are highly trained. The perceived safety of being close to support or the fear of being lost instinctively tends to make a threat that isn’t highly trained “bunch up” or stay in closer proximity while moving through terrain that provides limited visibility. Likewise if a natural obstacle forces the threat to split his forces (say between those before it and those beyond it) the threat leader may not be in direct control of up to half of its assets. In a dense swamp or heavily wooded area the threat may not be able to keep all of his assets in view or not take certain assets with him. As an example a technical (civilian pickup with a gun mounted) isn’t going to have the same capabilities to cross all of the terrain dismounted troops would. Likewise when terrain presents a narrow winding corridor like a road at the bottom of a valley or along a steep hillside that disrupts a threats ability to maneuver his assets while mounted.
So how can we exploit natural obstacles? It’s going to be difficult because chances are most of your Defensive Priorities are going to be static and there’s not a lot you can do about that. But by situating things like observation posts, checkpoints, small encampments, and even caches in the footprint of natural obstacles you can possibly prevent their detection by the threat and afford them some protection. Some protection. No position is ever entirely safe. The key thing to remember here is that when you place such positions take into account that the threat may assault them – so be sure to have more than one direction of travel out of any position like this if you have to bug out.
Typically the most effective ambush sites take advantage of natural obstacles as well. Example: the Mujahedeen in Afghanistan most often used constricted routes that paralleled steep cliffs to ambush Russian armored columns from the high ground by catching semi-isolated elements outside of the view of supporting armor or above its maximum weapon elevation (how high they can aim). In such ambushes frequently Russian tanks would be unable to move up or back to support the lighter vehicles or get enough elevation to fire on the Muj positions. Additionally The Muj made it common practice to have at least one natural obstacle between them and the threat thereby allowing themselves some protection from frontal assault. This is an example of exploiting a natural obstacle.
A key thing to take into account is the threats composition. A local gang of dirtbags likely won’t have the training nor equipment to scale a sheer cliff or ford a river with vehicles. Those same obstacles would be almost insignificant to a trained team of troops. The local SWAT team isn’t going to be as proficient as those troops crossing a heavy swamp but probably have better command and control than the dirtbags. Take your perceived threats capabilities and measure them against the natural obstacles in your AO.