Mortars

[Compass Rose]

MORTARS

By Marc “Bayonet” Bellizzi

In the little world of each combat commander, mortars represent another gem in ‘their empire’. The fact that ‘my mortars’ as my commander once put it, were always ready and available to fire at his whim, was a priceless fire support commodity.

7-1. FUNDAMENTALS

A successful commander understands that effective use of all available weapon systems will determine the outcome of a battle. Mortars are a combat commander’s primary source of responsive, accurate indirect fire support. Their rapid, high-angle, plunging fires are invaluable against targets in defilade (dug in), which are not vulnerable to attack by direct fire. They are especially effective at suppression, obscuration (smoke) and illumination on the battlefield.


In the attack, mortars suppress and fix the enemy. In the defense, mortars force attacking enemy vehicles to button-up, cause attacking troops to go to ground, break up attack formations, and canalize attacking forces into engagement areas where direct fire weapons can concentrate and kill them.



Mortars are particularly effective against soft skinned vehicles and unprotected personnel, causing nearly half of all casualties in WWII. So why do they seem so ineffective on the ‘virtual battlefield’?


In wargames, mortars are often misunderstood and misused. With each tube individually controlled and fired by the player, they are lobbed haphazardly across the battlefield, one round here, one round there, and the resulting lack of visible casualties quickly leads to frustration. This frustration eventually results in the mortars ‘sitting it out’ in the rear, taking little or no part in the battle. If you follow the precepts of doctrine I lay out below, you should start to see your mortars play a more important role in your wargaming.

7-2. ORGANIZATION

Mortars are organic to foot infantry, mechanized infantry, airborne and armored companies and battalions. Assigned to the headquarters element, or the weapons company (or both), they are organized into their own platoon.


A company’s mortar platoon typically consists of 2 squads with 2 x small caliber tubes each, for a total of 4 tubes (sometimes a third tube was added to each squad, or a third squad of 2 tubes was added that brought the total to 6 tubes in a company). These small caliber tubes have to be light and man-portable, so they usually are not bigger than 80mm.


This support is always considered ‘DS’ (direct support) to the company and on call for the company commander to provide support to the platoon (or platoons) engaged in combat.


At the battalion level, a mortar platoon consists of 2 to 4 squads with two tubes each of larger caliber guns (80mm to 120mm). In the larger 4 squad platoon, 2 squads can be combined to give two sections of 4 tubes each.


This support is always considered DS to the battalion and on call for the battalion commander to provide support to the company (or companies) engaged in combat.

7-3. EMPLOYMENT

The Company mortars are usually employed as a single platoon, all firing at the same target. They typically move and deploy in close proximity to each other since fire missions are simply ‘yelled’ across the group (rarely does anyone other than the mortar platoon leader have a radio). Many times the company mortars simply use line of site (direct fire) to fire at their targets. On the wargame battlefield, a player should have his company’s mortars either adjacent, or one hex apart (in line of site), of one another to simulate this.


The battalion mortar platoon may be employed by platoon, by section (half a platoon), or squad. The versatility of these various combinations gives the battalion commander the flexibility to provide anywhere from 2 to 8 tubes worth of mortar rounds on a target or series of targets impressive when you consider that massing 8 tubes on a target in Squad Battles equates to around 24 rounds on target per turn.


If firing by sections or squads, the elements do not have to be positioned near one another for the platoon to be employed as a platoon. The battalion mortar platoon has the necessary radios, equipment and personnel to conduct such fire missions from distinctly different locales by sections. If broken down into squads (a set of two tubes), the mortars are sometimes doled out to the various Company Commander(s) to employ at their discretion in the Direct Support role.

7-4. TECHNICAL DATA & RELATION TO SQUAD BATTLES

To understand mortars, and how and why they are employed the way they are, we must first dive into some technical info.

• 1) Hexes in Squad Battles are about 40 meters across; this 40 x 40 size equates to 1600 square meters of area in a hex.
  
• 2) Individual mortars in Squad Battles usually fire 3 rounds per turn.
  
• 3) A 60mm mortar has a lethal bursting area of 20 meters - this does not mean it will kill everything within 20 meters, but simply that anything in that range from the blast could be killed. Beyond this range, you will usually only wound someone.
  
• 4) 81mm & 120mm mortars have lethal bursting radii of 30 meters and 60 meters each. By inference, this means they have greater killing power round for round, but it is not exponentially greater; likewise, they usually only wound beyond these ranges.
  
• 5) In World War II all mortars fired ground burst HE rounds (no airburst, which is significantly more lethal to troops in the open or open top trenches airburst was not available until late ’44, and even then only to US troops).
  

I will show you what this means in Squad Battle terms.

If a flat, open hex is 40 x 40 meters, ideally a player must fire four rounds of 60mm fire (or two rounds of 81mm) just to blanket the entire hex with any chance of lethality (to picture this, draw a square box 40 x 40 meters, then cut the box in half length-wise and in half height-wise. You should see four small boxes. Each is a 20 x 20 meter box). One can see that a single 60mm mortar cannot blanket a hex in one turn on its own (remember 3 shots per turn). Likewise, an 81mm mortar cannot expect to blanket a whole platoon area (7-10 hexes). The 120mm mortars can cover a platoon sized area just barely.


In fact, the US Army Mortar Manual FM 7-90 states that “Against a standing, platoon-size enemy unit in the open, a 60-mm mortar squad (two tubes) that fires six rounds per mortar should inflict about 20 percent casualties. If the enemy is prone, these fires should inflict 8 - 10 percent casualties. Thus a light mortar section's FFE should seldom consist of any less than six rounds for each mortar, and often will require more to significantly affect the enemy platoon, especially in un-open terrain.”


Integrating the US Army’s figures in Squad Battles, after the first 60mm round, an enemy squad goes to ground (prone). So we must assume we only get one round per hex out of 12 using the 20% figure, and the follow-on 11 rounds use the 10% casualty figure. One twelfth of 20% is 1.66%. Using a 30 man platoon as the target, 1.66% of 30 equals .48 of a man…so we should see, on the first round, anywhere from zero to one casualty per squad targeted. The follow-on 11 rounds now using the ‘prone 10% figure’ can expect to kill one or two additional men).


So what does all this mean in wargaming? It confirms that mortars are best employed as a mass group all firing on the same target. For two 60mm mortars firing on a squad, expect to fire two turns (12 rounds total) to get one to three kills. Any additional turns will only kill, on average, one man every two to three turns.


For two 81mm or 120mm mortars firing on a platoon, expect to get three to six kills (the same ratio per squad as the 60mm) per platoon, or 2 to 5 kills on an individually targeted squad (remember once they go prone they are harder to kill). Any additional turns should kill one man about every two to three turns.


Not great numbers for the 60mm, and only marginally better for the larger guns. Put the enemy in improved positions, and the casualty rate drops 10% of the prone 10% figure, or to 1%; expect one kill every 4 to 8 turns with any size mortar. Put them in a house or bunker and your chances of a kill are slim.


When it comes to suppression, however, mortars start to play a significant role. In fact, according to FM 7-90, after one 60mm round, an area 35m around (basically one hex) will have about a 50% chance of suffering suppression (suppression defined as the effect produced in the mind of the enemy that prevents him from returning fire or carrying on his duties). We see this immediately when a fired on unit must go to ground. Within three or four rounds we start to find enemy units ‘pinned’. Likewise, with the 81mm and 120 mm mortars, we should see a platoon (7-10 hexes) go to ground in one or two rounds and some units in the area become ‘pinned’ in a few more rounds.


What this shows us is that as in real life, the purpose of SB mortar fire is two fold in the attack, it helps keep the enemy suppressed and fixed so your troops can close with his positions and destroy him, and in the defense it is used to break up enemy troop concentrations (with suppression) and canalize and force the enemy into engagement zones where full direct and indirect fires can destroy them.

7-5. IN THE OFFENSE

In a movement to contact, sections will be ‘leap frogged’ forward so that at any one time, one section is available for support for the battalion and the other is moving.


In a deliberate attack, the mortars are moved as close as possible to the front lines, while still maintaining cover, to provide additional firepower. As a rule of thumb, position them so the target is around one-half the mortar’s max range. Having mortar firing positions with good cover is often more important than the one-half maximum range rule.


Since mortar fire is so accurate, keep your tubes firing on the enemy during your attack until the last possible moment; then shift your fires to the backside of the enemy positions to prevent enemy reinforcements from reaching them. This is called isolation.

7-6. IN THE DEFENSE

In the defense, mortars are plotted just like artillery, having targets plotted and identified along the likely enemy avenues of approach. In particular, a location where direct fire weapons cannot shoot is where mortars should be targeted, to get enemy units that are hiding in dead space.


Any obstacle not covered by both direct and indirect fires can be obscured and breached. High explosive mortar fires can effectively prevent enemy forces from breaching an obstacle. Mortar fire is preferred for this task since it is always available as DS to the battalion commander. Its use permits the field artillery to concentrate destructive fires against enemy formations backed up behind the obstacle.


Closely coordinated mortar fire can increase the effectiveness and survivability of antitank weapons significantly. The antitank unit commander can be given priority of mortar fires or even control of the mortars. Mortar squads, sections and platoons support the anti-armor battle in many ways. The HE fires force tank crews to button up. This reduces their field of view and their ability to detect friendly forces. The larger mortar tubes can even immobilize vehicles. Mortar smoke rounds can also be fired to isolate the lead element of an advancing enemy force from the main body. The antitank guns can then attack this isolated element, free from enemy fires. Mortar smoke can be placed between the antitank guns and the enemy to aid the guns in their displacement out of initial firing positions to alternate ones. As the smoke clears, the enemy will be hit from previously ‘undetected’ (new) positions.

7-7. DISPLACEMENT

Since mortars have such a high trajectory and slow speed, the firing location can be pinpointed quickly by enemy counter-battery radar. Mortar units will usually fire a volley and then displace to a new location. Similar to the ‘leap frog’ style of movement, when one section is displacing, another should be already set-up ready to provide fire. In this way, there is continuous coverage, while increasing the life expectancy of the mortar units.

7-8. OBSCURATION (SMOKE) & ILLUMINATION

Mortars are excellent for employing smoke and illumination rounds. They are accurate (compared to artillery), and can build a good screen quickly, especially when fired as a group. Illumination rounds can be placed right where the player wants with mortars, and since they are fired one round at a time with a mortar, there is less ‘waste’ of precious ‘illum’rounds.


During an enemy attack, mortar smoke should be fired in front of the enemy overwatch or Base of Fire position, so that his supporting fires are masked. Smoke may also be used to obscure obstacles from attacking enemy forces, so as the smoke clears, your direct fire units can slaughter the stalled forces.


In the attack, smoke can cover your movement, as well as cover any obstacle breaching you must do.

7-9. FINAL THOUGHTS

Hopefully the player has a better appreciation of how mortars work and how to employ them on the war-game battlefield. Employed in multi-tube groups, all firing on the same target, mortars provide excellent results, especially considering the small number of rounds expended to achieve those results.


Mortar fire, being much more accurate and suffering less scatter than artillery, is excellent for close indirect support. Mortars can truly be an asset, ultimately reducing the amount of casualties a player incurs by helping suppress the enemy.

Sources:

SH 20-19 Artillery Employment and Capabilities, US Army, 1994

TM-E 30-451 The German Armed Forces, US Army, 1945

FM 71-1 The Tank & Mechanized Inf Cbt Tm, US Army, 1988

US Army Infantry School CATD training supplements, US Army, 1995

FM 7-90 Tactical Employment of the Mortar, US Army, 1992