Mortar: The Whispering Death from Above

The mortar is a deceptively simple weapon, a testament to the enduring power of a well-understood principle of physics: what goes up must come down. At its core, it is an Indirect Fire weapon, a category of ordnance designed not to shoot at an enemy, but over to them. Characterized by a relatively short, often smoothbore barrel fixed at a high angle (typically 45 to 85 degrees), the mortar lobs its projectile in a steep, parabolic arc. This allows it to bypass obstacles, walls, and the crests of hills, delivering explosive, smoke, or illumination rounds with plunging fire into trenches, fortified positions, and reverse slopes that are immune to the flat trajectories of rifles and most Cannon. Unlike its larger cousins, the howitzer and the field gun, the mortar is traditionally a muzzle-loading weapon of intimate scale, operated not by a distant artillery corps but by a small crew nestled within the infantry ranks. It is the foot soldier's personal artillery, a provider of immediate, on-demand devastation, whose life story is a dramatic cycle of invention, obsolescence, and brutal, battlefield-driven rebirth.

The story of the mortar does not begin with Gunpowder or even with metal, but with a fundamental human problem: the wall. For as long as humanity has built fortifications to protect itself, others have sought ways to overcome them. The direct assault was costly, the siege was slow, and so a third way was born from the minds of ancient engineers—the art of lobbing death from a distance, over the very ramparts designed to keep it out.

Long before the first chemical propellant echoed across a battlefield, the sky was already a domain of warfare. The earliest ancestors of the mortar were the great siege engines of antiquity and the Middle Ages. Weapons like the Roman onager and ballista could hurl stones and massive bolts, but it was the medieval Trebuchet that perfected the art of high-angle bombardment. This elegant monster of timber and rope was a masterpiece of mechanical engineering, using a massive counterweight to swing a long arm, slinging its payload in a graceful, towering arc. The Trebuchet did more than just batter stonework. It was a weapon of immense psychological power. It could hurl not just stones, but also incendiary mixtures, diseased animal carcasses, and even the severed heads of captured enemies, a grisly form of early biological and psychological warfare. For the defenders huddled behind their walls, it was a terrifying experience. The enemy was unseen, the whistling approach of the projectile was the only warning, and the destructive power came from an uncaring sky. This experience—the helplessness against an unseen foe delivering death from above—is the foundational psychological trauma that the mortar would inherit and perfect. The Trebuchet etched the principle of indirect fire into the military mind, establishing a need that would one day be filled by a more compact and ferocious successor.

The arrival of Gunpowder in Europe from China in the 13th century was the great catalyst of military revolution. The slow, methodical power of torsion and counterweights was about to be replaced by the instantaneous, thunderous force of controlled chemical explosion. The first firearms were crude, dangerous, and often as much a threat to their users as to the enemy. But among these early experiments, a new class of weapon emerged: the Cannon. The earliest cannons, known as bombards, were behemoths of cast iron or bronze. They were squat, pot-bellied, and fired massive stone or iron balls. Weapons like the “Pumhart von Steyr” or the “Dulle Griet” (Mad Meg) were not elegant field pieces but immobile monsters of the siege. Their primary purpose was to batter down walls with brute force. However, their very design—a short, wide barrel—made them suitable for a secondary role. By propping their muzzles upwards at a steep angle, these bombards could be used to lob their projectiles over castle walls, mimicking the trajectory of a Trebuchet but with far greater destructive potential. The Siege of Constantinople in 1453 is a landmark event in this transition. The massive bombards commissioned by Sultan Mehmed II, including the famous Great Turkish Bombard, demonstrated the awesome power of gunpowder artillery in siegecraft. While primarily used for direct fire against the legendary Theodosian Walls, the concept of using large-caliber, short-barreled guns for high-angle fire was firmly established. These early bombards were, in function if not in name, the first gunpowder mortars. They were a clumsy, transitional form, the roaring dinosaurs of the gunpowder age, but they carried within their iron hearts the seed of a new kind of weapon.

The path from a massive, immobile bombard to a distinct and recognized weapon required a leap in both technology and tactical thinking. This leap occurred during the Renaissance, an age of scientific inquiry and military innovation, where the weapon finally gained its iconic name and a more specialized form.

The name “mortar” itself is a clue to its early form and function. It is derived not from a word for war or destruction, but from the humble mortar and pestle used by alchemists and apothecaries for centuries to grind chemicals and herbs. The new weapon, with its short, bowl-like shape, looked remarkably like the chemist's mortar. The round, fused projectile, dropped into the muzzle before firing, completed the analogy as the “pestle.” This name, born of a simple visual resemblance, stuck. By the late 15th and early 16th centuries, these purpose-built mortars were becoming a standard feature in siege trains. They were typically cast in bronze or iron, with a fixed base or mounted on heavy wooden beds. Their projectiles, called “bombs,” were hollow iron spheres filled with Gunpowder and fitted with a simple time Fuze—a wooden plug filled with a slow-burning powder train. The gunner would light the Fuze on the bomb and then, with a second flame, ignite the main propellant charge in the mortar's breech. It was a perilous and imprecise art. A Fuze that burned too fast could cause the bomb to explode in the barrel, destroying the weapon and its crew. A Fuze that burned too slow would allow the enemy to extinguish it or even hurl it back. Despite these dangers, the mortar proved its worth, capable of terrorizing garrisons and starting fires within fortified cities.

For two centuries, the mortar remained a heavy, specialized siege weapon. Its transformation into a tool of the infantry, a truly tactical weapon, was the work of one of the great minds of military engineering: the Dutch Baron Menno van Coehoorn. Living in the late 17th and early 18th centuries, Coehoorn was a master of fortification and siegecraft, a direct rival to the famous French engineer Vauban. Coehoorn recognized that the nature of siege warfare was changing. It was becoming a slow, grinding affair of trenches and counter-trenches, a methodical approach towards the enemy's walls. In this environment, a heavy, immobile mortar was of limited use. What was needed was a weapon that could be brought forward with the attacking infantry, a light and mobile source of high-angle fire to clear enemy trenches and forward positions. His solution, developed around 1701, was the Coehoorn mortar. It was a small, bronze weapon with a 4.5-inch bore, mounted on a simple wooden block with carrying handles. Weighing under 150 pounds, it could be carried by two men and put into action quickly. It was the first truly portable mortar. Its effect on the battlefield was profound. No longer did infantry have to wait for the main artillery train to be brought up. They now possessed their own organic firepower, capable of lobbing small bombs directly into the enemy earthworks just ahead of them. The Coehoorn mortar became immensely popular and was widely copied, seeing service in conflicts like the War of the Spanish Succession and the American Revolution. It represented a crucial shift in thinking: the mortar was no longer just for breaking cities, but for breaking enemy formations.

Despite Coehoorn's brilliant innovation, the mortar was about to enter a long period of relative obscurity. The neat, linear battlefields of the 18th and 19th centuries had little use for its unique capabilities. It took the horrific stalemate of a new kind of industrial war to thrust it back into terrifying prominence.

The 18th and early 19th centuries were the age of linear tactics. Armies faced each other in open fields, in tightly packed lines of infantry, firing volleys from smoothbore muskets. In this context, military art prized mobility and flat-trajectory fire. Artillery trains were streamlined, as exemplified by the French Gribeauval system, which standardized cannons to be lighter, more mobile, and more accurate. The focus was on field guns that could maneuver with the infantry and cavalry, delivering canister shot and roundshot directly into enemy ranks. Sieges still occurred, but they were often resolved by powerful, accurate cannons that could breach walls from a safe distance. The small Coehoorn mortar, with its short range and inaccurate projectiles, seemed a relic. It was a weapon for the messy, close-in fighting of the trench, and for over 150 years, that kind of fighting was largely absent from major European wars. The mortar was not forgotten, but it was relegated to a minor, specialized role, a curious antique in the arsenals of armies mesmerized by the disciplined spectacle of line battles.

The wake-up call came in the East, during the Russo-Japanese War of 1904-1905. The Siege of Port Arthur was a shocking preview of the horrors that would define World War I a decade later. Here, armies armed with modern magazine rifles, Machine Guns, and rapid-firing artillery dug into the earth, creating vast networks of trenches, protected by barbed wire and concrete machine-gun nests. Suddenly, the cannons of the 18th-century battlefield were rendered impotent. Their flat trajectories meant they could fire for days without disturbing the enemy soldiers huddled in their deep trenches. Direct fire was useless. The Japanese infantry, launching wave after wave of frontal assaults, were slaughtered in unimaginable numbers by Russian machine guns. Both sides desperately needed a weapon that could reach into those trenches. Out of necessity, the mortar was reborn. The Russian defenders, under General Roman Kondratenko, improvised. They took 47mm naval gun barrels, mounted them on wheeled carriages at a high angle, and created makeshift trench mortars. They even designed a new type of projectile for them. The Japanese, facing the same problem, quickly developed their own crude mortars. These improvised weapons proved devastatingly effective, lobbing explosives with pinpoint accuracy into the trenches that were immune to other forms of attack. Military observers from Europe and America watched in grim fascination. The lesson of Port Arthur was clear and bloody: in the face of modern firepower and field fortifications, the high-arcing trajectory of the mortar was no longer an antique curiosity but an absolute necessity.

If Port Arthur was the prophecy, the Western Front of World War I was its brutal fulfillment. The war quickly devolved into a static hellscape of trenches stretching from the Swiss border to the North Sea. Millions of men lived and died in a subterranean world of mud, barbed wire, and constant fear. In this environment, the mortar found its ultimate calling, evolving from a forgotten tool into one of the most iconic and feared weapons of the Great War.

At the war's outset, most armies had only a handful of heavy, outdated mortars. But the reality of trench warfare created an urgent demand for a new solution. The British found their answer in the genius of a civil engineer named Sir Wilfred Stokes. In 1915, he designed a weapon that would define the modern mortar and become the template for nearly all that followed: the Stokes Mortar. Its design was one of almost absurd simplicity, a testament to the idea that the most effective solutions are often the most elegant. It consisted of three main parts:

• A smoothbore metal tube.
• A flat, heavy baseplate to absorb the recoil and prevent the tube from burying itself in the mud.
• A lightweight bipod to support the barrel and allow for aiming.

But its true genius lay in its firing mechanism. Unlike older mortars that required complex loading and ignition, the Stokes mortar operated on a “drop and fire” principle. At the bottom of the tube was a fixed firing pin. The shell itself was a self-contained unit, with a propellant charge in its base and a primer. To fire, a soldier simply dropped the shell, tail-first, down the muzzle. The shell would slide down the tube, its primer would strike the fixed firing pin, and the resulting explosion would send the shell on its way. This system allowed for a phenomenal rate of fire—a well-drilled crew could fire over 20 rounds a minute, showering an enemy trench with a terrifying deluge of explosives. The Stokes mortar was light enough to be carried and operated by infantry, bringing immense firepower directly to the front line. It was the perfect trench sweeper. Soldiers gave it the chilling nickname, the whispering death. Because its shell travelled at subsonic speeds, it made very little sound as it flew through the air. The first indication of an attack was often the faint, almost gentle whistle of the falling bombs, a sound that grew into a terrifying shriek in the final second before impact, giving soldiers no time to take cover. It was a weapon of immense psychological dread, a constant, unseen threat that preyed on the nerves of even the most hardened veterans.

While the British perfected the simple, rapid-fire infantry mortar, the Germans pursued a different philosophy. Their primary trench weapon was the Minenwerfer, which translates to “mine thrower.” These were more complex and robust than the Stokes, essentially short-barreled, rifled howitzers. The German Minenwerfer came in light, medium, and heavy varieties. Being rifled, they were more accurate and had a longer range than the smoothbore Stokes. They were also breech-loading, which was slower but allowed for a more powerful propellant charge and a heavier shell. While the Stokes was a weapon of rapid saturation, the Minenwerfer was an instrument of deliberate destruction, capable of leveling bunkers and obliterating sections of trench with a single, massive projectile. The conflict between the Stokes and Minenwerfer philosophies—simplicity and rate-of-fire versus complexity and precision—was a technological debate that would continue to shape mortar design for decades. But both weapons proved the same point: in the static slaughter of the trenches, the high, arcing flight of the mortar was king.

The Great War cemented the mortar's place in the modern arsenal. The decades that followed were not a period of radical reinvention, but of continuous refinement, transforming the crude trench sweepers of 1918 into the sophisticated and indispensable tools of today's infantry.

The brilliant “drop and fire” concept of the Stokes mortar was its greatest strength, and in the years after WWI, it was this design that became the global standard. The most significant improvements came from the French firm Brandt. The Brandt Mle 27/31 mortar refined every aspect of the Stokes design. It featured a more stable baseplate, a more robust and easily adjustable bipod, and vastly improved ammunition with better aerodynamics and more reliable fuzes. This French design was so successful that it became the archetypal mortar of the 20th century. It was licensed, copied, and reverse-engineered across the world. The iconic American 81mm M1 mortar of World War II was a direct copy of the Brandt design. The Soviet 82mm M-37 mortar, which would see service for over half a century, was heavily based on it. Brandt had created the definitive form of the modern infantry mortar, a design so effective that a soldier from 1940 would find the basic operation of a mortar from 2020 remarkably familiar.

In World War II, the mortar was everywhere. It was a standard component of virtually every infantry battalion in every major army. Its versatility was its greatest asset. A platoon under heavy machine-gun fire could use its mortars to suppress the enemy position with high explosives. An attacking force could use mortars to lay a thick smoke screen to cover its advance. A unit defending a position at night could use illumination rounds, or “star shells,” to turn night into day and expose an infiltrating enemy. The war also saw the proliferation of heavier mortars. While light (60mm) and medium (81/82mm) mortars remained the workhorses of the infantry company, heavy mortars of 120mm caliber were introduced at the battalion and regimental level. The Soviet 120-PM-38, often mounted on a simple two-wheeled carriage, was a prime example. It could deliver a shell with the destructive power of a light artillery piece but was far more mobile and easier to conceal. This blurred the lines between infantry support weapons and traditional artillery, giving commanders on the ground a powerful and responsive tool for shaping the battlefield.

The mortar's evolution continues into the 21st century. While the fundamental form remains unchanged, modern technology is enhancing its capabilities in remarkable ways.

• Materials: Modern mortars use advanced metal alloys and composite materials, making them lighter and more portable than ever without sacrificing strength.
• Fire Control: The old system of optical sights and manual calculations is being replaced by digital, computerized fire-control systems. A soldier can enter target coordinates from a GPS device, and the system instantly calculates the correct bearing and elevation, allowing for incredibly fast and accurate targeting.
• Ammunition: The most revolutionary change is in the projectiles themselves. The development of Guided Munition technology has given birth to the “smart” mortar round. Rounds like the American XM395 Precision Guided Mortar Munition (PGMM) are fitted with fins and a GPS or laser guidance system. After being fired in a traditional ballistic arc, they can adjust their flight path to steer directly to a target. This transforms the mortar from an “area weapon,” good for suppressing a general location, into a precision instrument capable of hitting a specific vehicle or fighting position with a single round.

Today, the mortar remains what it has been since its brutal rebirth in the trenches: the infantry's most intimate and responsive form of artillery. Its journey from a simple stone-throwing machine to a smart-weapon platform is a microcosm of military history itself. It is a story of a simple concept—the power of the arc—that has been repeatedly adapted to overcome the challenges of the battlefield. It is the whispering death, a sound that has echoed from the walls of Constantinople to the fields of Flanders and the mountains of Afghanistan, a constant reminder that sometimes the most effective path to an enemy is not the straightest, but the highest.