Introduction

The 3rd Battalion, Royal Australian Regiment (RAR) was directed (via Land Trial 04/16) to employ the 60mm M224 Mortar at the combat team level in support of a range of tasks throughout 2017. The aim being to assess the feasibility of a lightweight mortar capability within Royal Australian Infantry units, under operationally representative environments, in order to inform the Chief of Army decision for its introduction into service. This task fell to Charlie Company and was achieved during the conduct of the 3rd Brigade Ready Combat Team (RCT) / Ready Battle Group (RBG) War Fighter Exercise (WFX) and Exercise Talisman Sabre 17.

Debate regarding provision of a lightweight mortar for employment within rifle platoons of the RAR has increased in the current decade. It has previously been raised formally in the Australian Infantry Magazine and informally across other common forums such as offices, messes and breezeways. Much of the reasoning that I have read and heard from those opposed to the concept of a lightweight mortar focuses on comparisons with other weapons such as the Light Weight Automatic Grenade Launcher (LWAGL). Such comparisons are often logically unsound as they generally revolve around capabilities that are common to the weapons being compared, with statements such as “we don’t need a mortar to provide obscuration, illumination or airburst effects...the 84mm Medium Direct Fire Support Weapon (MDFSW) already provides those capabilities.” While this particular assertion is not incorrect, I think it misses the point.

An argument for the efficacy of a lightweight mortar must be based on the capabilities that set it apart from the other weapons. Even a casual comparison between a lightweight mortar, LWAGL and 84mm MDFSW reveals obvious differences: a lightweight mortar is a simple, handheld, agile weapon system that is capable of firing various ammunition natures and fuse combinations at high trajectories from behind cover by a single operator; a LWAGL is a crew-served, tripod mounted, heavy, direct-fire weapon capable of firing rounds in quick succession from an ammunition belt or large-capacity magazine; and the 84mm MDFSW is a portable, shoulder-controlled, large-signature direct fire weapon capable of firing a variety of ammunition natures and fuse combinations from prone, kneeling and standing positions by a two-man crew.

Characteristics

So why should a rifle platoon field a lightweight mortar? What actually sets it apart from the other weapons in a rifle company’s arsenal?

High Trajectory Fire – Mortar fire is characterised by a high trajectory which allows the operator to fire the weapon from protected positions behind whatever cover is available such as walls, buildings, vehicles or from within a mortar pit. The high angle at which the round impacts at the terminal end of the ballistic arc allows the operator to achieve effects on targets that are behind available cover.

Low Signature – A lightweight mortar has no Back Blast Danger Area (BBDA) that reveals the firer’s position.

Range Spectrum – The M224 in the Handheld mode is able to engage targets from as close as 70m out to maximum range of 1300m.

Agility and Portability – A lightweight mortar can be deployed in under 20 seconds at targets within a 360° arc and then relocated immediately after firing. The M224 when configured in the Handheld mode weighs 9kg and is capable of being fitted with a sling or carried in bespoke load carriage equipment. Each bomb, depending on the nature, weighs approximately 1.7kg and measures 38cm in length.

Variety of Ammunition Natures and Fuse Actions – Modern mortars are capable of firing High Explosive (HE), Illumination (ILLUM), infra-red illumination and phosphorous rounds that provide target marking, obscuration and incendiary effects. Modern mortar rounds are typically fused with multiple options for action on the target including point detonation, delay, airburst and mechanically timed.

Simplicity – A lightweight mortar is an uncomplicated system lacking complex working parts generally consisting of a barrel, baseplate, trigger, firing pin and sight assembly.

Indirect Fire – Traditionally the M224 in the Handheld mode is a line-of-sight weapon meaning that either the operator, or an observer co-located with the mortar, is able to observe the target and direct adjustments. However, if a grid to the target can be determined, then so can an accurate range and bearing which can be used to aim the mortar in order to interdict targets using indirect fire. Devised by Charlie Company during the RCT/RBG WFX as a way of engaging targets from inside the urban environment without revealing the mortar’s position, this method of aiming was coined the “Hybrid Method” as it integrated the theory of indirect fire with handheld mortars. The Hybrid Method is unorthodox and not codified in doctrine yet the casualties reported via instrumented Battle Damage Assessment (BDA) proved it to be remarkably effective method of engagement.

Employment Concepts

Qualification Training – By way of a formal ‘Handheld mode only’ course it’s feasible for a soldier to become qualified in six periods of instruction using the following pathway:

2 x periods - characteristics, description, how the weapon works, safety precautions, strip and assemble, cleaning and maintenance

2 x periods - care and preparation of ammunition, degrees of weapon readiness, immediate action and stoppage drills

1 x period - weapon qualification test

1 x period - qualification practice: firing one round of either practice or HE followed by one White Phosphorous (WP) round. The requirement to fire one round of either practice or HE corresponds to current qualification practice requirements for other small arms weapon systems such as the SL40, M79 or 84mm MDFSW; while observing the effects of a single WP round provides the operator an understanding of how prevailing atmospheric conditions will affect the smoke cloud.

Doctrine and Range Safety – In order to determine where a lightweight mortar best resides within doctrine we first need to look at how the weapon will be employed in combat then build a framework that supports that idea. If we assume a lightweight mortar is a rifle platoon weapon and despite it being classified as a mortar, the method of employment and supervision is more aligned with a Direct Fire Support Weapon (DFSW) than an 81mm F2 Mortar, then a suitable weapon pamphlet would exist within the Support/Crew-served weapon series of the LWP-G 7-4-X catalogue. This puts the lightweight mortar in a position for inclusion into LWP-G 7-3-1 Australian Defence Force (ADF) Range Orders (Land) as a Category B5 DFSW range weapon. Category B5 DFSW ranges provide good observation and fields of fire as well as the infrastructure required that allows non-participating personnel to seek shelter behind blast and splinter proof cover. The fact that the qualifications required to be Officer In Charge and Safety Supervisor Category of B5 DFSW ranges are granted on the ADF Range Qualification and Infantry promotion courses means that a rifle company could hypothetically raise, train and sustain the capability.

Clearance of Air – In the Handheld mode the M224 ammunition has a time of flight ranging between 7-24 seconds with a ceiling Maximum Ordinate (MAXORD) of 680ft Above Ground Level (AGL). In combat situations clear air should be achieved in the same manner as other rifle company weapons in that, prior to firing, the operator or supervisor ensures the space between the weapon and the target is clear. This level of air clearance must be preserved in order to maximise a lightweight mortar’s speed of response which allows it to influence the initiative. It is also commensurate with the air clearances for Javelin which has a MAXORD of 518ft AGL or the 84mm MDFSW which has a MAXORD of 874ft AGL when firing ILLUM.

Conclusion

The 60 mm M224 Mortar configured in the Handheld mode proved to be a game-changer for Charlie Company. The instrumented BDAs were disproportionately high when compared to the ease with which the weapon was employed, supporting the assertion that a lightweight handheld mortar is a suitable and effective platform to be organic to rifle platoons.