"On Mortars, Artillery, and Indirect Fire" by Tyler

I will begin by saying that I spent four and a half years as mortar infantry. I did a tour in Afghanistan with Bravo Company, 1/501^st Parachute Infantry Regiment, and a tour in Iraq with Bravo Company, 4/23^rd Stryker Infantry Battalion. Therefore I apologize in advance to all the gun bunnies that read this and wonder why I don’t focus as much on their discipline as I do the mortar. I would rather not guess on what intricacies are involved in your trade. This paper will be split into two parts. The first will describe how indirect fire works.  The second part will give my observations on how indirect fire is used and misused in the current conflicts.

 

Indirect fire has been with us almost as long as the invention of gunpowder. It didn’t take long for someone to realize once something can launch a small object far, it can launch a bigger object far as well. As tactics evolved, so did the methods in which indirect fire was delivered to the battlefield. The modern day models have led to two different paths: mortars and artillery.

 

   

The major difference between the two is that mortars deliver their rounds in a high, arching fire. Artillery pieces tend to fire in a lower arc over a longer distance. You can think of it as simply a larger rifle. A second difference is that artillery pieces tend to be larger in both firepower and caliber. The largest mortar piece the US military fields is a 120mm mortar. The largest artillery piece is a 155mm cannon. The advantage of artillery is the greater distance and firepower, while mortars are able to deliver highly accurate rounds with impressive mobility, speed, and cover. A 120 mm mortar team can consist of three men, fit in the back of a standard humvee, and set up and take down in a matter of minutes.

 

However, effective indirect fire comes from three sources. The first is the gun crew, generally anywhere from 2 to 5 personnel. The second is the fire direction control (FDC), who is generally two soldiers. Occasionally there will be a third running the radio as a Radio Telephone Operator (RTO) if there is a surplus of personnel. This is the exception, however. The two soldiers working as FDC will function as a primary, who will be working on a mortar ballistic computer. The second soldier will be working as a check, to make sure that the data entered and received matches up with the primary’s data.

 

The third part of indirect fire comes from the Forward Observers (FO). FOs may refer to infantry soldiers in the field who call in fire. However, dedicated FOs are an MOS in and of themselves, assigned to the Artillery Branch. They tend to work in pairs, either moving far ahead of friendly lines or on the front line, calling in fire on targets. It takes a special kind of mentality to be an effective Forward Observer, and part of that is an extreme attention of detail. All the FOs I have worked with were meticulous about data, possessed nerves of steel under fire, and loved their work. I do not know if the work makes the man or the man is attracted to the work; I believe that the answer is somewhere in between.

 

Now that the major three parts of effective indirect fire have been discussed, I will lay out how a typical call for fire occurs. The FO spots a target, and decides what kind of mission he will call. A grid mission is just that. The FO estimates the map grid the target is on, and calls it in to the FDC. The second kind of mission is a polar mission. The FO gives the FDC his position, and calls the azimuth and distance the target is from him.

 

Once the FO has given the mission type and data to the FDC, the FDC will generally use the mortar ballistic computers to compute the data in question. Once the data is computed, and double checked, the firing data is given to the gun crew. This data comes in the form of MILS (horizontal) and ELEVATION (vertical) on the gun sight. As the gunner dials in the data, the assistant gunner will manipulate the gun to level the bubbles on the gun sight. Once the bubbles are leveled, the gun is ready to fire. After each round the bubbles are checked, and re-leveled as necessary before firing again. The FO will adjust the data from where the rounds land, or call for “fire for effect”, at which a number of rounds are fired at once.

 

Data must be accurate. In training, one mil off is “acceptable”. During combat, the data must be exact. Failure to do so can result in courts martial if something goes horribly wrong. Gunning is serious business, and often the gunner is a specialist, sometimes a private first class. This is a tremendous amount of responsibility for an enlisted soldier, and gunners tend to be steady, intelligent, and reliable.

 

Gunners may also fire independently of an FDC or FO on targets visible in the open. This is called direct lay and is complex to describe the particulars of. In a nutshell, it involves the gunner using the explosions to direct his rounds on the targets in question.

 

 

Part 2: Indirect Fire and COIN Warfare

 

It is my belief that indirect fire, by its very name, has acquired a bad name in command circles. Captains and Lieutenants are, in my experience, enthralled with the experience of calling in air strikes with laser guided 500 pound bombs. In the same breath, they will deride indirect fire as being too inaccurate.  Often much of this extends from ignorance. Many infantry commanders spend their O-1 to O-3 careers as infantry platoon commanders before assuming command of a company. They have little experience with mortars in a tactical sense. To paraphrase Anthony Swofford, they know that mortars are a good thing to have, but what the hell are they supposed to do with them?

 

In Afghanistan, we were in contact for almost ten minutes while the company commander tried to get helicopter support, before he allowed the single 60mm mortar to fire. Six rounds later the enemy stopped firing. Due to there being a mine field between us and the enemy, no battle damage assessment was available, but the FO Chief on scene believed that we had killed them all. To this captain’s credit, he became a true believer shortly afterwards.

 

Mortars are used to great effect by the Afghanis, where the mountainous terrain tends to preclude the use of artillery. However, the high arching fires are perfect for the terrain of Afghanistan. These battles tend to be indirect “knife fights” of a kilometer or less, and can become duels between gun teams.

 

The Iraqis often used mortars as well, to target Forward Operating Bases and troops in the open. However, we were precluded from firing mortars into Mosul, even while under direct contact, and also into Tal Afar. Instead command believed that helicopter gun strikes (with Hellfire missiles) were more accurate. I don’t totally understand this, but believe that helicopters are more PR friendly to the high command.

 

Our total lack of use resulted in the trained mortar soldiers running a detainee center, then being sent to the line infantry platoons, and finally ending up being part of the company commanders Tactical Action Command with the forward observers assigned to the company.

 

This action is writ large in the bigger Army, with artillery units unable to qualify with their guns. In the new COIN Army, artillery units have been retrained as military police and civil affairs troops, as their accurate and dependable firepower is considered unnecessary in the hearts and minds style battle.

 

The blast radius of the smallest mortar, the 60mm mortar, is roughly 30 yards. The range is 2490 meters. With current technology, FO’s are able to get 10 digit grids, which are accurate of up to one meter.

I use these stats to give the audience a basis before I describe why the current roles of engagement are foolish and almost treasonous.

The total fear of using indirect fire seems to come from the high command’s nightmare of massive civilian casualties in the current Afghanistan operation. This speaks of a complete lack of trust in the enlisted soldiers and non commissioned officers responsible for indirect fire and their training. There is no excuse not to call in mortars on troops in the open, with no civilians around, even if they are firing in an urban area. However, when you’re sitting in Kabul designing a rules of engagement to be incredibly media friendly, this is the sort of thinking that works.

 

When you’re a grunt pinned down by automatic fire, unable to pop your head up because of the volume of firepower coming your way, and need help, it is criminal to be unable to call in quick and accurate indirect firepower.

 

I hope this essay helps the civilian public understand the application and use of indirect fire in our current conflicts.

Comments

[Etienne]

Thank you. This site's supply of military information & knowledge based on experience is greatly appreciated.

[The Twisted Genius]

Tyler, thanks for taking the time to prepare this. I think it's a great primer on mortars and indirect fire. I am disheartened by your observations on commanders' reluctance to use their organic mortars in Iraq and Afghanistan. In my day we were always admonished to keep the crew served weapons manned no matter how short handed we were at the company level.

I also don't understand why a commander would want to rely on air assets which he doesn't control and may or may not get at a critical time for his fire support. Using one's wholly owned mortar section seems like a more logical first choice. Given that pilots are loath to share airspace with artillery and mortar rounds, perhaps higher headquarters are reluctant to do the necessary coordination to ensure that air assets (including resupply and medevac) can be used at the same time as indirect fire. Do you have any thoughts on this?

[William P. Fitzgerald III]

Pat Lang,

That's an excellent piece on mortars and indirect fire in general by Tyler. However, I looked in vain for references to the M-10 plotting board, aiming stakes, lensatic compass, and those good U.S. Army binoculars. Is the 60 mm mortar now in the T.O.E. of the weapons platoon?

Referring to the general trend of comments concerning the "Battle of Marjah", r.o.e., and the action in Kunar Province described by Jonathan Landry. First, given the purpose of our operations in much of Afghanistan and the nature of the fighting, which seems to be almost entirely skirmishing against lightly armed and elusive
guerillas, I think the rules are appropriate in much of the country. But, then, there's the problem with rules. That doesn't mean they're appropriate everywhere.

I have some questions and comments about the action, described by Landry, last September. Given that the force was a mixed marine and army group of NCO and officer advisers, along with some Afghan police, they didn't have (and wouldn't be expected to have crew served weapons. So, no mortars. Also the fire support arrangements seem to have been in the nature of an informal agreement. At the same time as their engagement, one of those outposts in a nearby valley was, according to Landry's account, under a heavy attack. My question is who had priority of fires and was any artillery in direct support of he expedition in question? If not, and it seems not, isn't it possible that supporting fire was not available because of loose and informal arrangements and the absence of a field order specifying fire support, rather than having been denied because of r.o.e.?

WPFIII

p

[VanD]

THX. An interesting and appreciated read, providing good background for this article, involving 81mm mortars: http://www.warisboring.com/?p=4085

In this case (not a major battle) there seemed to be no hesitation to use mortars, or call in air strikes, even with a group of reporters observing.

[Bob Bernard]

Cost always enters in. A gps guided 155mm round costs about $85K and a dumb 155 round about $500.

If you are firing at an area target, you would want to use the dumb rounds. The reduced accuracy would result in better coverage of the target.

GPS guided rounds can hit 10m of the target and dumb rounds have a circular probable error of about 200m.

I don't know if gps guided rounds fall under different rules of engagement in Afghanistan, but they should.

[Tyler]

Twisted Genius,

Thank you.

Once while at National Training Center, we were hit by a Multiple Launch Rocket System. The commander was told to get rid of a certain amount of personnel as casualties. "I'll get rid of my ash and trash. Mortars, FOs, stay here," he said.

Needless to say, it was endearing to here him arguing with Charlie Company's CO and battalion mortars to shift fires over and receive repeated denials.

I honestly believe that many officers are influenced by what they see on TV over and over again. That of helicopters and jets acting in a CAS role, with a captain hunkered down calling in fire. The fact is that many captains just aren't interested in their mortar sections.

This is exacerbated by many battalions moving to an "arms room" concept, with all the units mortar infantry being assigned to battalion, and being parceled out to the company. The main proponents of this seem to use the argument "Ranger Battalion does it this way, so should we." I don't see any real advantage to this system, and the CO tends to distrust his mortars even more, since he does not even take a hand in their training.

Finally, I believe that perhaps the fact its an officer flying the helicopter as opposed to an enlisted man, may have something to do with it as well. That's just speculation on my part though.

WPFIII,

I did leave those out, and you're right that explaining how the mortar is "aimed" would have been a great help, since it seems like so much wizardry ("I can hit those guys over those mountains!") to the casual observer. So mea culpa there.

When I left the Army, the 60mm mortars were a squad sized element in the company, except for those who adopted the "arms room" concept I mentioned above.

I can't comment too much on the rest of what you posted, except that "informal" agreements tend to break down when the shit hits the fan. Why so many commanders are willing to leave behind their indirect crew served seems to be prevalent in the Army though. They wouldn't be so willing to leave behind their weapons squad, I think. Perhaps an issue at the
initial training level?

Bob,

The GPS mortars I mentioned were not built into the round. Instead the gun itself was GPS guided.

So with these high speed, incredibly accurate weapons, mounted in Strykers, what did the battalion ended up doing with them once we were in Iraq?

They pulled the guns out, lined the bottom with kevlar blankets, and used them as troop carriers.

Ladies and gentlemen, the new Army.

[William P. Fitzgerald III]

Tyler,
Thanks for all the info.
I was being my facetious self when I mentioned aiming stakes, plotting boards, and things, as I surmised that there must be new gizmos in the system. GPS Mortars! I sounds like an infantry company no longer has a weapons platoon. Is that so?

WPFIII

[Thomas]

Tyler,

An interesting read, good job.

You think that in trying to reduce errant airstrikes, a solution would be to put more empahasis on mortar teams with patrols.

[Tyler]

WPFIII,

I believe only the Rangers use the weapons platoon now. Light machine guns were part of a weapons squad, assigned to each platoon. The anti tank element and mortar element were each grouped into the HQ platoon, before the AT element was ripped apart and given to the line platoons. The 60mm mortars were part of the HQ platoon, in the end.

Thomas,

Yes. I think that no matter what DoD flunky you get standing up there talking about the "accuracy" of 500 lb laser guided bombs to reporters, it is still a bomb. You drop it on a block, you're ruining a lot of people's day.

You use a 60mm mortar on "delay", you're going to punch through the ceiling of the building and blow up inside the room.

I think if commanders were more willing to invest more interest in their mortars, they wouldn't end up being pinned down waiting on air strikes b/c they left their tubes back in the FOB.

We could get the guns set up and send rounds down range inside of three minutes. That's setting up the system, running out poles, and plugging in the elevation and deflection. You have to have a shit hot fire support team, but it can be done.

[Tyler]

Plus, outfitting and equipping a mortar section probably costs as much as one laser guided bomb. Or a whole pallet of mortar rounds.

So perhaps that has something to do with it as well.

[Tyler]

Last comment, I swear.

A 60mm mortar system can also be hand fired on charge 0 or charge 1. Anything above that and you're risking a broken hand or accuracy (you can fire it with a belt if you must.)

My CO in Iraq was shocked you could use it this way. He was more shocked that I could put rounds on anything he pointed out on the range reliably. So you have commanders not understanding the capacity of the weapon systems beneath them. Always a problem.

[Michael]

Just a dumb civie question, but is it 'indirect' fire in the sense that the target is not acquired by the person firing, rather the FO?

[SAC Brat]

Being a math and physics enthusiast I am always amazed at the precision required to hit targets you can't see, targets that are moving (particularly naval targets) and barrage techniques such as walking barrages as well as what is required to coordinate indirect fire with ground movement. I've read and heard numerous accounts of creative forward observers being considered artists with their imaginative application of fire support.

My grandfather had been in the signal corp in France and would tell us about how some German soldiers had some fun with him by using artillery to shoot off the top of the telephone pole he was working on. That may be why his buddy and him, as musicians later on, liked to play Ocktoberfests in the 1970/80's so they could end the evenings by playing a fast paced medley of beer hall songs and seeing how many of the old boys forgot themselves and jumped up and threw salutes at the end.

[john]

My artillery experience was from 1967. We used M109 Howitzers (unit originally had split trails). We spent the bulk of our time in base camp firing H&I's with occasional direct support missions. We generally registered the guns once a week and could generally hit a 55 gallon oil drum out at about 8k on the first or second shot. Generally within 50 meters the first shot. Our biggest accuracy problem was that the maps and picto maps did not have good ground control (sometimes being off by as much as 800 meters). All of our firing data was calculated from firing tables and a plotting board. I believe WPFIII mentioned circular probable errors. I never encountered that terminology. We did have range probable errors (which of course were much greater than lateral or deflection errors (which were quite small with the M109's when we first got them).

FADAC was just coming into use back then. The guns were using collimaters instead of aiming stakes.

I imagine that artillery now uses centrally managed fires (originating and calculated at the battalion level or higher).

I'm curious about what range a dumb 155 shell has a circular probable error of 200 meters. Must be a gun. I remember a 175 mm was lucky to gt within 800 meters out past 24k.