Field artillery has been called “The King of Battle.” And for good reason. Great generals throughout history have lauded the power and necessity of artillery in battle. Artillery wins battles and therefore could win wars. Mortars are basically the light artillery of the infantry. The U.S. military uses a variety of mortar calibers for infantry support. The 81mm mortar is a portable, mobile, medium mortar at the infantry’s disposal.

Mortars are indirect-fire weapon systems. The term “indirect fire” means firing at an enemy without having a direct line of sight. A rifle or a tank, for example, are direct-fire weapons. You see the enemy, you aim, and fire that munition directly at him. Mortars are indirect-fire weapons that rely on mathematical calculations to fire a munition at a high angle, which then arcs down onto the intended target.


The Infantry Mortar Platoon

US Infantry mortar platoon composition
Unit composition of the infantry mortar platoon taken from ATP 3-21.20. Unclassified.

In the U.S. Army and the U.S. Marine Corps, the 81mm mortar is a battalion asset. This means that each infantry battalion has a mortar platoon providing indirect fire support for the other infantry companies in the battalion. This mortar platoon has four squads of infantrymen, plus a fire direction section (squad), that makes the fire control calculations. Each mortar platoon has four 81mm medium mortars at its disposal — one for each squad. They also have four M120 heavy mortars, as well, but typically each squad only operates one mortar at a time.

Mortar systems can provide three different types of “fires” — types of rounds and engagement — for the infantry units they are supporting.

Firstly, high explosive rounds (HE) are used to suppress or destroy enemy infantry, weapons, and equipment. They are also used to deny enemy movement and mobility in certain areas.

Obscuration rounds, or smoke rounds, create a smokescreen within the target area. This smokescreen can either help conceal the movements and locations of friendly units, or obscure the vision of enemy units.

Thirdly, illumination rounds. These are fired directly into the sky at night over a target area. Once the shell explodes, a bright flare ignites and offers light and visibility of the area below. These can also include infrared (IR) illumination, not visible to the naked eye without the use of other optic systems.


The M252 81mm Mortar

Mortar tube
Lance Cpl. Kyle J. Palmer (left), holds a mortar tube steady as Lance Cpl. Samuel E. Robertson (right), mortarmen with the 81mm Mortars Platoon, Weapons Company, Battalion Landing Team 2nd Battalion, 7th Marines, 31st Marine Expeditionary Unit, grabs another mortar round during a joint live-fire exercise. (USMC)

The M252 is the standard medium weight 81mm mortar in service with the U.S. military today. Each mortar requires a team of five infantrymen to properly field and operate it. The M252 weighs about 91 pounds. Its tube has a length of four feet two inches. The Army and Marines have developed a lighter version of the M252, the M252A1, and the M252A2, respectively. These systems will be fielded in the coming years; older systems will simultaneously still be in service.

At this caliber, the M252 81mm mortar is practically a light artillery piece. The kill radius of the 10-pound HE round is approximately 35 meters. The maximum effective firing range is 5,700 meters, with a minimum range of 80 meters (that’s really close).

With a maximum rate of fire of 33 rounds per minute, and 16 rounds per minute over a sustained period of time, these mortars offer a high level of capability. The mortar can unleash a lot of explosive firepower within a target area over a short period of time. Do not discount or underestimate the small and mighty mortar!

Because numbers and data can actually be fun and interesting, here are more facts about the M252 81mm mortar. What would you guess the price tag for each system is? The answer is $25,000 — a little higher than I had guessed, myself. And to piggyback on that little trivia tidbit, the average price of each 81mm HE round, is about $600.


The 81mm Mortar in Service Today

American soldiers mortar Taliban
U.S. Army Soldiers with 10th Mountain Division, fire mortar rounds at suspected Taliban fighting positions in eastern Nuristan province, Afghanistan. (Photo by Sgt. Matthew C. Moeller/U.S. Army)

The 81mm mortar has been used in recent conflicts around the world. For example, in my first firebase in Uruzgan, Afghanistan, we had an active mortar pit within the firebase for base defense. We employed both 81mm and 120mm mortars. Mortars are highly effective in environments like Afghanistan.

In general, mortars are best in open areas or terrain and less desirable in urban environments. The reasons are obvious, as the risk for collateral damage is high when civilians are present. However, do not discount the role of the 81mm mortar in urban environments. Their ability to deny key-terrain access to the enemy is important, even in an urban space. Further, in some cases, mortars might be more desirable than artillery or airstrikes, which can create more devastation.

The 81mm mortar is an effective battlefield weapon that allows infantry commanders to employ decisive tactics. It offers a good balance of firepower and mobility. As the 81mm mortar can be employed and fired quickly it can unexpectedly shift the momentum of a battle when used effectively.