Mortar (weapon)

• 1. Introduction

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  The mortar is one of the oldest and simplest artillery weapons still in active use, yet it earned its name not from any battlefield invention but from the humble kitchen tool it resembled. Early versions were iron bowls, nearly indistinguishable from the pestles and apothecary vessels found in homes and workshops, and that visual echo is where the word "mortar" comes from. Today, a modern mortar is a lightweight, muzzle-loaded tube fixed to a base plate, carried by a single soldier, and capable of dropping explosive shells almost vertically onto targets that conventional artillery cannot reach. How did a siege weapon so heavy it could barely move become something one person carries on their back? And how did that journey, stretching from a 1413 naval battle in Korea to the muddy trenches of the Western Front, produce the weapon that militaries around the world still depend on today?

• 2. Korean Origins

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  The earliest reported use of a mortar occurred in Korea during a naval battle in 1413. Korean gunsmiths at that time developed a weapon called the wan'gu, a name meaning "gourd-shaped mortar." The earliest version of the wan'gu dates back to 1407, and credit for inventing it is generally given to Ch'oe Hae-san, who lived from 1380 to 1443. He was the son of Ch'oe Mu-son, himself a celebrated figure in Korean military history, who lived from 1325 to 1395. The weapon traveled to other contexts. During the Ming dynasty, the general Qi Jiguang, who lived from 1528 to 1588, recorded the use of a small cannon called the hu dun pao that bore a close resemblance to a mortar. Meanwhile in Europe, the first recorded use of a mortar in siege warfare came at the 1453 siege of Constantinople by Mehmed the Conqueror. Three years later, an Italian account by Giovanni da Tagliacozzo described the 1456 siege of Belgrade, where Ottoman Turks deployed seven mortars that launched stone shots high enough into the air that observers posted ahead of time could warn troops to take cover before the projectiles landed.

• 3. From Siege Weapon to Field Artillery

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  For most of its early history, the mortar was a tool of sieges, not field battles. Weapons like the Pumhart von Steyr in the 15th century were large and heavy and resisted easy transport. Mortars played a notable role during the Venetian conquest of Morea between 1684 and 1699, and during that campaign an ammunition depot inside the Parthenon was blown up in 1687. A significant shift arrived in 1701 when Baron Menno van Coehoorn invented an early transportable mortar. His design fired an exploding shell with a fuse lit by the hot gases of firing, and it proved popular enough to drive demand for a new kind of naval vessel, the bomb ship. British forces used more mobile mortars as field artillery at the Battle of Glen Shiel in 1719, during the suppression of the Jacobite rising. The high-angle trajectory gave these weapons a clear advantage over standard field guns in the rough terrain of the West Highlands of Scotland. By the Napoleonic era, the mortar had largely fallen out of general use in Europe, surviving mainly as the Manby Mortar, deployed along coastlines to fire rescue lines to ships in distress. Mortars saw heavy use again during the American Civil War from 1861 to 1865. At the Siege of Vicksburg in 1863, General Ulysses S. Grant reported improvising mortars by boring out logs of tough wood to accept 6 or 12 pound shells and binding them with iron bands. Grant noted they worked as well as Coehorns, successfully throwing shells into enemy trenches. During the Russo-Japanese War of 1904-1905, Lieutenant General Leonid Gobyato of the Imperial Russian Army pioneered indirect fire from closed positions in the field, and working with General Roman Kondratenko, designed the first mortar built to fire navy shells.

• 4. The Stokes Mortar

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  Sir Wilfred Stokes devised his mortar design in 1915, and that moment is where the modern, person-portable mortar was born. Trench warfare had created urgent demand for a weapon compact enough to be used under cover, yet capable of dropping shells into enemy trenches where conventional artillery shells, flying on a flat trajectory, could not reach. Stokes' first design was rejected in June 1915 because it could not use existing British ammunition stocks. It took the intervention of David Lloyd George, then serving as Minister of Munitions, and Lieutenant Colonel J. C. Matheson of the Trench Warfare Supply Department, to push manufacture forward. The resulting weapon was a smoothbore metal tube mounted on a base plate and lightweight bipod. A bomb dropped into the tube struck a fixed firing pin at the base, which detonated a primer and launched the round. The original model could fire as many as 25 bombs per minute and reached a maximum range of 800 yards. After the war, engineers developed a modified version firing a fin-stabilised streamlined projectile with a booster charge, extending the range to over 2,500 yards and pushing the rate of fire to as many as 30 bombs per minute by World War II. The French produced improved versions as the Brandt Mle 27 and the Brandt Mle 31. Those designs were copied, with and without license, around the world and became the prototypes for nearly all subsequent light mortar development.

• 5. The Spigot Principle

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  The spigot mortar inverts the basic arrangement of a tube weapon. Instead of a barrel that the projectile sits inside, a spigot mortar is a solid rod onto which a hollow tube built into the projectile fits over the top. The propellant charge is contained in a cavity at the top of that tube, and a long firing pin runs the length of the spigot to set it off. This configuration means no barrel in the conventional sense, which allows ammunition of almost any weight and diameter to be fired from the same launcher. The firing unit itself, being just a baseplate and rod, is smaller and lighter than an equivalent tube mortar. Britain used a 230 mm petard mortar on the Churchill AVRE tank in World War II, while Japan deployed a 320 mm Type 98 spigot mortar at the battles of Iwo Jima and Okinawa. Britain also fielded the Blacker Bombard and the PIAT as anti-tank launchers built on the spigot principle. One striking application was the Hedgehog launcher, mounted on ships to fight submarines. It fired 24 spigot mortars arranged to fall in a diamond pattern ahead of the ship; a projectile would detonate upon striking a submarine, and the pattern was sized so that any submarine partially within the zone would be hit at least once. After Belgium developed the Fly-K, a near-silent spigot mortar that traps propellant gases to suppress the sound of firing, the French adopted it into service as the TN-8111. Spigot mortars largely fell out of military favour after World War II, though small-calibre versions survive today in a non-military role, launching foam training targets for retriever dog training.

• 6. Improvised and Insurgent Mortars

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  Insurgent groups have long constructed mortars from heavy steel piping mounted on steel frames, firing standard rounds, repurposed gas cylinders packed with explosives and shrapnel, or any improvised munition at hand. The Provisional Irish Republican Army called these weapons "barrack busters." In the Syrian civil war, such improvised mortars became known as hell cannons, described by observers as "wildly inaccurate" and responsible for thousands of civilian deaths. A more developed example emerged from the Sri Lankan civil war. The rebel Tamil Tigers used a weapon called the Baba mortar from the 1980s onward; early Baba rounds contained tar that caused fires on impact. The Tigers later developed the Pasilan 2000, a heavier system mounted on a mobile launcher carried on a tractor. Its warhead weighed 70 kilograms, filled with TNT, and it could reach a range of 15 to 25 kilometres. Analysts noted its features were similar to those of the Chinese-made Type 82 130 mm 30-tube multiple launch rocket system, which the Palestinian Liberation Army had introduced in the early 1980s. Despite its greater lethality compared to the Baba, the Pasilan 2000 saw limited use during the Eelam War IV ground operations.

• 7. Precision and Modern Variants

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  Most modern mortar systems still follow the four-component layout of barrel, base plate, bipod, and sight, with calibres typically running from 60 to 120 mm. A 120 mm mortar bomb carries roughly the same explosive yield as a 152 or 155 mm artillery shell, a result of the thinner-walled construction that smooth-bore, fin-stabilised rounds permit. Precision guidance has entered the picture. The XM395 Precision Guided Mortar Munition, a 120 mm round developed by Alliant Techsystems, uses a GPS guidance kit derived from Orbital ATK's Precision Guidance Kit for 155 mm artillery and fits directly onto standard 120 mm mortar bodies by replacing the fuse. Sweden's Strix round, manufactured by Saab Bofors Dynamics, uses an infrared imaging sensor to guide itself onto tanks and armoured vehicles after launch from a standard 120 mm mortar. Normal range is up to 4.5 km, which a sustainer motor can extend to 7.5 km; the seeker is designed to ignore targets that are already burning. Israel Military Industries developed the GPS and laser-guided GMM 120, while Elbit produced a separate Israeli guided round called Iron Sting. Russia fields the laser-guided KM-8 Gran. At the vehicle end of the spectrum, the Russian 2S4 Tyulpan is a self-propelled 240 mm heavy mortar and among the largest mortars in current use, while Israel's Merkava tank carries a 60 mm mortar as a secondary weapon. The AMOS, or Advanced Mortar System, takes integration further still, using a 120 mm automatic twin-barrelled breech-loaded turret that can be mounted on both armoured vehicles and attack boats.

• 8. The Largest Ever Built

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  From the 17th century to the middle of the 20th century, engineers periodically attempted to build mortars of staggering scale, reaching calibres of up to one metre. One early landmark was Roaring Meg, with a barrel diameter of 15.5 inches, which fired a 220-pound hollow iron ball filled with gunpowder during the English Civil War in 1646. Henri-Joseph Paixhans developed what became known as the Belgian Monster Mortar, 24 inches in calibre, in 1832, and it is the distinction of having been the only one of the largest mortars to actually be used in combat, at the Battle of Antwerp that same year. Robert Mallet designed Mallet's Mortar in 1857, reaching 36 inches. The United States developed the Little David at 910 mm for use in World War II, though it never saw combat. Germany's Karl-Gerat, at 600 mm, holds the record as the largest mortar to see combat in modern warfare.