Ordnance ML 3-inch Mortar

History

Some of the lesser known British weapons of war that served during WWII were Ordnance, ML Mortar, 3". The weapon was in service throughout the conflict, enabling British Army and Commonwealth personnel to drop explosive projectiles at enemy positions and troop concentrations.

The original version lacked the range of its wartime contemporaries, but as the war progressed, the mortar system was almost powerless, and by the 1960s it became the standard British infantry mortar weapon.

During World War I, the British Army relied on their tried-and-true 1917 3-inch Stokes mortar system, which proved to be a sturdy weapon after the war. The interwar years proved to be a rather slow period for the British Army to develop weapons and occasionally consider increasing the overall infantry-level firepower. It was originally envisioned that a company would be armed with light machine guns to bring ample target fire to the herd.

While this design direction retained some advantages consistent with the popularity of automatic weapons, it proved expensive to manufacture, not to mention carrying a machine gun that staggered infantry. Instead, the Stokes mortar design was modified in the 1920s and developed into a more modern form of combat.

Its 81mm projectile is always great for indirect fire/long-range combat, which has been proven time and time again in the Great War.

Stokes' basic design was changed to "Ordnance, ML Mortar, 3" Mk II, and production brought it to what was required when war officially broke out in Europe in 1939 to end World War II quantity. Led by well-trained and well-equipped German troops, British Army personnel launched the new Mk II to fight the Axis forces.

The British gun had an operating weight of 112 pounds, fired 10-pound shells at 1,600 yards at a muzzle velocity of 650 feet per second, and required at least three specially trained personnel to operate.

After some operational experience, a serious design flaw came into play, especially when comparing the Mk II to the German infantry mortar system (i.e. the GrW 34 series). The Mk II was simply too rich, and required British troops to get very dangerously close to the enemy so that the system could have any type of tactical effect on a given battle. German mortars had a range of 2,600 yards, while the British Model Mk II could only reach 1,600 yards under ideal conditions - a 60% difference.

So British engineers went back to improving the Mk II's design.

After a period of revision and testing, followed by an in-depth evaluation, a new 3-inch mortar form was produced with an extended barrel, a new projectile with increased load, and inherent Longer range (up to 2,800 yards). Over time, production met demand, and the British army was now on an equal footing with the Axis armies.

Meanwhile, British infantry and Commonwealth units were relegated to use captured German or Italian mortars and their corresponding ammunition stocks, while the Mk II was redesigned.

As the war progressed, the British 3" mortar was further modified, including a new aiming system as well as a revised baseplate. A more portable form was also developed for use by paratroopers, some of which were used in tropical and mountainous environments in the Far East, where British and Commonwealth troops were entangled with those of Imperial Japan.

Ultimately, the British 3-inch mortar proved to be a reliable and robust weapon system, removing all the limitations of the original production model and improving it. Crews quickly learned the advantages of their 3-inch mortars, and they could even reach a minimum range of 125 yards if needed, while using altitude and propellant to fine-tune the mix.

This short-range capability could prove ideal for close support operations against advancing enemy forces.

In terms of design, the Ordnance ML Mortar 3 inches has a simple layout and general functionality. The design is characterized by its main components - namely the launch tube, base plate, bipod, sighting equipment and ammunition.

The system is an accurate 81 mm (3.2 in) caliber (though 3 in is used in the official name) and can fire standard high-explosive (HE) projectiles, smoke and flares. The mortar is 1.295 meters long and the barrel is 1.19 meters long. When the system is activated, it weighs 126 pounds, and when the weapon is disassembled for transport, it requires at least three people, each tasked with transporting a major component into battle.

Artillery elevation, limited to +45 to +80 degrees of firing and lateral angles, was 11 degrees in both directions. Pitch and roll controls are mounted on the bipod assembly, while the rear sight is identified along the barrel towards the muzzle end. 81mm shells weigh 10 pounds each.

This operation is a routine operation where personnel aim their weapons at the intended target area. A member then drops the ready-to-fire projectile from the muzzle, which falls from the launch tube and hits the firing pin on the base plate, igniting the internal charge propellant.

This explosion forced the projectile out of the barrel and along the basic trajectory. The crew can then modify the lateral and altitude based on where they landed on the previous lap and repeat the process again. The heavy base plate is used to dampen the violent recoil inherent in this weapon, while also serving as a third support leg in conjunction with the bipod assembly.

As an "indirect fire" weapon, a mortar is designed to strike an area rather than a single enemy force. Its high-explosive projectiles are very useful against enemy personnel concentrations.

Smoke grenades can be used to cover friendly tactical operations, while flares are used to mark enemy positions in low light conditions.

Typically 3" mortar systems are positioned by mortar crews, but the British Army uses their nimble little "universal carrier" tracked vehicles (detailed elsewhere on this page) to transport the guns to speed (please Note that the 3" mortar is not designed to fire from the vehicle itself, it must be unloaded and set to fire on the ground). This rapid transport allows mortar teams to quickly reach designated areas, equipped with ammunition supplies, and then disembark to install mortars and prepare them for firing. The crew can also dig into the surrounding land and create a depression in the ground for firing, providing the crew with basic protection from enemy fire. As long as the ammunition supply is imminent, the mortar team can deliver a steady rate of fire to the heads of friendly troops. The 3-inch design can also land in a hardened container in three main sections - the barrel and bipod, the base plate and the initial ammunition supply.

The paratrooper element just needs to recover the different parts, assemble the weapon and start shooting at the enemy.

Ordnance 3-inch mortars continue to be in service outside the UK and are in stockpiles in Australia, Canada, India, Ireland, Luxembourg, New Zealand and the Philippines. In the Philippines, 3-inch mortars fought against anti-Japanese insurgents during their occupation during World War II and remained in service until the 1960s.

From 1965 onwards, the wartime 3-inch mortar was inevitably replaced by the L16A1 81-mm mortar, which was attempted by the modern Inga-Canadian joint design.

Specification

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