Welcome to “Fire Mission Battery!” A podcast history of artillery.
I’m your host Jon Moore
Let’s get the questionable and problematic out of the way first: Mortars.
For the majority of gunpowder history, mortars were shaped more like the kitchen mortar and pestle one finds in kitchens rather than the barrel, base plate and adjusting legs we see in the infantry’s mortar platoons.
They mimicked the high angle delivery of trebuchets. The effects of trebuchets in sieges was well known. They were a mature technology. In much the same way early motor vehicles were horse carriages, minus the horses so too were early mortars used as trebuchets had been without the woodwork: Large projectiles, muzzle loaded and discharged in high angle to attack walls and the infrastructure behind them inside the castle, township or city.
The high angle thing was something of a conundrum. The trajectory was subject to semi scientific investigation. From the Warfare History Network is a longish quote from the article, Famous Military Weapons: Mortars
Quote:
Predicting Trajectory
Well into the 16th century, mortar trajectory was reasoned to be most effective at an elevation of 45 degrees, and mortars were often cast as a single piece with an integrated bed fixed at that angle. This meant that mortars had to be moved or fitted with blocks and wedges to vary the trajectory when 45 degrees was found to be inadequate. Even into the 1750s, mortars were still being cast in this manner, inevitably requiring similar adjustments. But trunnions were now set back nearer the base of the mortar, making for an easier means of varying angles.
Practical science for aiming and ranging mortars grew out of nonmilitary pursuits, most typically surveying and navigation. But while mathematicians explained shot trajectory by means of geometry, the plain gunner still depended on his experience for expert aiming. Aside from books about gunnery for the few who could read, there were simple measuring instruments—the quadrant, shadow square, level, and plumb bob—to elevate the barrel and figure distance. Enterprising mathematicians and instrument makers such as Leonhard Zubler were quick to adapt designs used by surveyors, sailors, and astronomers for gunners as well. Standardization of charge and range produced fairly accurate rules for aiming and lobbing shots into the enemy.
End Quote
The practical use of mortars was generally understood from both theoretical and practical approaches.
The standardisation of charge and projectile, as mentioned above, made life easier but that quite often only referred to each weapon or battery. Over time the projectiles became generally smaller, depending upon use. At the Siege of Rhodes, 1480, the Knights Hospitallers made use of 635mm mortars in counter battery fire against the Ottoman 635mm cannon.
By placing the mortars behind the walls and utilising the high angle approach, the Turkish cannon, firing in low angle at those walls were left vulnerable.
The Hospitillers were still using stone projectiles but these were being replaced. Anti-personnel projectiles involving metal balls, a charge and a fuse developed during the 16th century. These were adapted to both cannon and mortars. The airburst from mortar fire could be devastating.
The use of mortars and their development declined to some degree with the growing changes to field pieces during the 19th century. The development of howitzers and indirect firing methods seemed to leave the mortar obsolete. Larger and smaller mortar types were used during the American Civil War, in siege work particularly. And this seemed to be the last hurrah for the type.
Yet German military observers, during the Russo-Japanese War of 1904-05, spotted a Japanese lightweight mortar. Not just lightweight and portable, the ammunition consisted of a compact areodynamic bomb with fins with a small propellant change at its base detonated by a firing pin when the projectile was dropped from the muzzle. These weapons were though simply shorter barrelled, muzzle loaded field pieces with large calibres and reduced weight. Wheels were fitted for transport and removed in action.
The Germans developed these into a type known as minenwerfer (literally “mine thrower”). A rifled mortar with calibres from 250mm to 305mm. The 250mm type being the standard issue once WWI was underway. The British version was developed in 1915 in response to being on the receiving end of the minenwerfer. Developed by Wilfred Stokes, the design was originally rejected because it required the manufacture of its own ammunition. That is, extant ammunition types could not be adapted to the new weapon. Eventually Lloyd George at the encouragement of Lieutenant-Colonel J. C. Matheson of the Trench Warfare Supply Department who had observed the weapon in trials, forced the weapon on the army.
Yet the inertia in military systems also created heavy, very heavy trench mortars:
Quote:
Heavy designs still prevailed for traditional fortification bombardment. Various trench mortars, among the biggest being the British 9.45-inch Flying Pig and the Austrian 305mm Skoda, required cannon-like wheel carriages. New models with more options such as battlefield illumination at night and smoke screening, would emerge during World War II. At the same time, heavy mortars were mounted on vehicles such as jeeps and half-tracks for use on European battlefields.
End Quote
Back to WWI.
The minenwerfer was considered a useful weapon despite the obvious drawbacks from hindsight. We all know what a Stokes pattern mortar looks like, the German military did not at the time of the minenwerfer’s development. So it came with wheels, a recoil system and massive base plate.
Quote:
The weapon was far more efficient than its artillery counterpart. In comparison the 7.7 cm FK 96 n/A needed to be towed by a team of six horses, compared with a single horse for the LMW, additionally the LMW could be moved around the battlefield by four men. The minenwerfer was cheaper, costing only one seventh as much as the artillery gun, and the ammunition was cheaper. Since the muzzle velocity, and thus firing shock of the minenwerfer was low, a variety of explosives that would usually be unsuitable for use in artillery were used to fill the shells. In any case, TNT explosive was reserved for use in artillery shells. Typically the explosives used in the minenwerfer were ammonium nitrate-carbon explosives. However the sensitivity of the explosives occasionally made them detonate in the tube. There were a large number of these incidents, one of which claimed the life of Karl Völler, head designer of Rheinmetall, in 1916. These problems, however, were eventually overcome.
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Given the increasing restrictions on German industry as WWI progressed, the cost advantages of the minenwerfer became ever more important. Germany entered the conflict with 44 of these weapons and ended with 1,234 heavy, 2,361 medium and 12,329 light versions. The pics on the website show the light version.
The continued development of the howitzer and the introduction of the Stokes pattern mortar pretty much sounded the death knell for this in-between weapon.
The minenwerfer was of the traditional heavier type mortar weapon, the Stokes is something more revolutionary. Lightweight, mobile and better at close support in situations from static defence to rapid advance. If you look at the pics on the website, the Stokes is a huge leap in imagination from the minenwerfer.
Now to a more detailed look at the Stokes pattern weapon.
The Stokes mortar was 81mm or 3in calibre. The barrel was a seamless extruded single piece of metal. No joints, no weakness. As with all artillery, the quality of the projectile and the propellant matters as much as the weapon. More operators have been killed and wounded by faulty ammunition and propellant than failure of the weapon since about 1800.
A definition of terms will help:
Quote:
A modern mortar on the Stokes pattern is usually a simple, lightweight, man-portable, muzzle-loaded weapon, consisting of a smooth-bore (although some models use a rifled barrel) metal tube fixed to a base plate (to spread out the recoil) with a lightweight bipod mount and a sight. They launch explosive shells (technically called bombs) in high-arcing ballistic trajectories. Mortars are typically used as indirect fire weapons for close fire support with a variety of ammunition.
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That the Stokes model has taken over is not that surprising. The traditional style as exemplified by the minenwerfer has been superseded by howitzer. Large projectiles, fired at high angle on increasingly mobile platforms. There’s a pic of a minenwerfer readied for transport and another showing it being moved. It would have been possible to manoeuvre it about by hand but compared to the Stokes model, much more slowly.
Today, mobility in mortar deployment is a chief area of tactical application. With a 120mm bore now the standard size for heavy tactical applications.
The thing is we always seem to have a way of going back to the future. The older style heavy mortars from the past are now mounted on tracked based mobile platforms with, surprisingly, pairs of barrels. Various countries have developed mortar systems along these lines using the latest smart bomb technology, computer-based firing options, and GPS-based ranges adapted to armored vehicles and tank-like platforms. Contemporary mortars include the AMOS, AMS-II, Bighorn, CARDOM, and Dragon Fire systems. Pics on the website, link in the show notes.
In conclusion, the mortar has a long history in the story of artillery. The standard infantry models are less than 110 years old. The heavier, more traditional types have made a comeback.
Next month we’ll begin on field artillery. Now this is a huge area and I’ll sneak in through the sub genre of mountain artillery.
Thanks for listening, until next time, Ubique.
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Links
email: pod@firemissionbattery.com
Website: www.firemissionbattery.com
Famous Military Weapons: Mortars
https://warfarehistorynetwork.com/2016/01/24/famous-military-weapons-mortars/
Minenwerfer