Outdated Doctrine: The Construction of Mortar Firing Pits
By Captain Matt Swan
We need to take a look at how we train and employ our 81mm Mortar Platoon within the Marine Corps Infantry Battalion and break the bad trend of holding tight to outdated doctrine such as the construction of the Mortar Pit. I say this because I spent two years as an 81s Platoon Commander, and during this time I engaged in more conversations defending my position as to why I did not dig in my gunline on the ranges. The trend I have seen when it comes to expectations is among senior staff officers coming out to a training range to watch and visit my 81s platoon at their Mortar Fighting Position (MFP). This expectation is that they will arrive to see all eight of the cannons dug into nicely constructed mortar pits spaced out correctly in a “Lazy W” formation as “per the doctrine.” But this doctrine is outdated, and our tendency to hold so close to the mortar doctrine when it comes to the construction of mortar pits is a recipe for disaster in a future peer-on-peer fight.
As the 81s CO, I would brief my training objectives and the conduct of the live-fire ranges. At the end, I would constantly be asked questions by staff along the lines of “So you are going to dig mortar pits, right?" I would then state that I had no plans to dig mortar pits, as I found them out of date, and that my training focus was working on the survivability tactics of my platoon. There would be counterpoints and a discussion of what the doctrine says, and maybe I should look into having my gunline dig pits anyway. This was the biggest battle I fought during my time as the 81s platoon commander. While there were some officers that would slowly agree with my reasoning, others would still hold to the “Book” doctrine and the listed reasoning behind the use of the mortar pit.
The Problem with the Current Mortar Pit
According to MCTP 3-01D Tactical Employment of Mortars, updated in October 2019, a basic mortar pit, referred to as a Stage 1, requires a single pit to be approximately 3-meter wide and a maximum of 1 ½ meters deep. That's almost 10 feet wide by 5 feet deep of digging! Anyone who has used E-tools to dig a proper mortar pit to the correct dimensions knows it’s a long and painful task. While this might provide some limited protection to the Marines from small-arms fire and shell fragments, it does absolutely nothing about overhead cover and concealment. As we have seen, the use of UAS coupled with fires has wreaked havoc on the battlefields in Ukraine on exposed artillery and mortar units.
The work on the construction of this Stage 1 pit further requires security as the work is being done. Security becomes an issue as half the platoon is posting security while the other half is digging and throwing dirt to make their pits. Once the pits are constructed and the guns are emplaced, this new position, often exposed to eliminate masking or overheard fire obstruction, acts as a huge target locator for enemy forces. The construction of mortar pits further hinders the platoon in combat operations. 81s should have the ability to keep up with and support the maneuver elements by using the target range criteria of the one-third, two-third guide, where “at least one-third of the weapon’s range behind the forward line of their own troops to support retrograde, and two-thirds of their range to the front of the forward elements of the supported friendly force” (MCTP 3-01D, 4-6). The platoon can clearly not accomplish this mission when constructing and sitting in a mortar pit.
Should the platoon be required to displace to a new MFP, the reality is that they will not have the time and energy to re-fill in their dug pits. This disturbed earth sets a pattern that can be located and soon traced by recon assets from both the ground and air. This could lead to enemy forces being able to possibly anticipate the next MFPs as well as confirm that there are 8 mortars operating in the AO. This doctrine of digging Stage 1 pits does nothing tactically but frustrate and tire out the Marines during operations while making them a lucrative target for counterfire.
Is there a time when the construction of mortar pits should be used in a tactical environment? Yes. Establishing an SOP as to when and where to construct the above methods of mortar pits should be discussed among the members of the platoon, with the goal of not emplacing the gunline out in the open. If a unit is going to remain at a location for an extended period of time, say 48 hours or more, the platoon should look to establish Stage 1 pits in a treeline. This includes the use of a technique that allows the guns to fire and then be covered back up with camouflage to prevent observation (think of a “gun port” style open and close style method). Additionally, the use of several mortar pits can be established at Forward Operating Bases (FOBs), with the guns rotated daily between the pits to reduce the loss of the guns due to observation and targeting by enemy fires.
Some Solutions for Training
According to MCTP 3-01D the “best positions are protected by both defilade and camouflage.” This is where commanders should focus their training. Forget the mortar pit. Focus on the occupation process of RSOP (Reconnaissance, Selection, and Occupation of Position) and displacement from that position following fire missions. Do not remain static. Being out in the open in an established position is an inviting target for ISR and counter battery fires. All members of the platoon should be thinking creatively as they train. Test out new ideas. Set up the gunline in a treeline. Practice transitioning from Shoot-and-Hide positions as much as possible in various terrain and situations. Time the setup, fire mission, and displacement of the platoon. Keep working on speed and accuracy drills while at the same time removing cumbersome equipment. Some of the lessons learned from mortar platoons in the war in Ukraine is that units have established SOPs with strict time limits: they had 10 minutes from the time the 1st mortar round goes down range to the time Russian artillery is throwing back counter battery fire on their location. This is the reality of the future fight our mortar platoons face. In the next fight, creativity and survivability tactics will keep the 81s on the field and able to support the maneuvering units in combat operations.
Conclusion
While digging mortar pits is something that should not just be forgotten, it should also not be the default answer and the main focus while training for the future fight. As General Mattis stated in his book Call Sign Chaos: Learning to Lead, "doctrine is the last refuge of the unimaginative.” Bottom Line: Ditch the Pit. Shoot – And – Hide!
Captain Matt Swan is currently the Commanding Officer for Company G, 2d Battalion, 24th Marines. He can be reached at mattwswan@gmail.com.
Good job articulating your concern w doctrinal mortar pits always being your highest priority of work.
Doctrine is no more than historical best practices...in previous wars/fights.
I’d say the mortar pit is still applicable when the section/platoon is expected to stay in one spot longer than expected. Guarding Forward Operating Bases, providing security to high value targets (airfields, logistics hubs).
During offensive combat while closing on an enemy, the digging of the pit would be much lower in the priority of work than seating baseplates by hand, establishing wired communications and masking the position from surveillance. Focusing on developing speed for displacement and emplacement is certainly a higher training requirement, but won’t alleviate all tasks. You’ve already identified current timelines of incoming artillery as 10 minutes, so practise getting into and out of new positions with accurate first round affects and displacement out of the firing position (beyond artillery fire and it’s ability to adjust onto you) within 8-9 minutes).
For the training environment, provide indicators to leadership on your learning priorities before they default to the one metric they are used to looking for (mortar pit). Point out your cold to hot firing position plan, allow them to see the movement from cold to hot, dismount, emplacement and time to first accurate shot on target. Demonstrate the proficiency of the FDC is getting the target sheaf correct on first shot even w non-standard layout of the section/Plt (let terrain dictate the layout for Survivability Vice a tape measure). First round affects have the highest effects before becoming suppressive only. Speed to first shot increases the likelihood of those affects.
As the Commander, you still have to teach and measure the mortar pit for your Platoon at some point in the training cycle to ensure everyone knows what right looks like. Perhaps that’s only once per 2 year cycle with higher priorities of work targeting the Survivability method of camouflage (creative use of non standard aiming stakes that blend in), displacement, emplacement, establishing comms, gaining rapid first round affects and signature management of all facets of the platoon, not just the guns themselves.
Perhaps the best answer is that of the LAV-mortar variant (enhanced). Perhaps w the change of war caused by the proliferation of drones and better satellite imagery, truck mounted mortars need to become obsolete, or at least give way to more mobile platforms that eliminate emplacement and displacement in lieu of speed into and out of their positions. The acquisitions cycle is too slow to keep up with the environmental conditions (foot mobile likely works better in urban areas, whereas vehicle mounted best in low population deserts).
The key takeaway is for Survivability, we can’t stay in place too long. That’s true until we manage to counter the new drone problem. Once we do counter this new disruptive force and regain full 3D mutual support, the mortar pit suddenly increases in value over constant movement.
Thanks for writing and kickstarting the conversation
Semper Fidelis
Jeff
From a former BN mortar PL in the Airborne Infantry:
Fully Agree.
Luckily I had great NCOs who shaped me and good leaders who allowed us to be effective.
We had towed 120s and this is where we focused our deliberate defense efforts.
In fact we did a defense LFX where we established a fire base in a triangle formation that culminated with a FPF and displacement.
But the 81s (and 60s) were always prioritized for hip shoots and set in a wood line with minimum necessary masking and overhead clearance.
Somewhere along the way, GWOT convinced the force we need 360 degree fires from mortars, and that’s just not sound in LSCO.
Great article CPT