Soviet M1938 120mm mortar.

[davebender]

6km max range.
.....10.5 cm leFH 18/40 howitzer = 12km.
about 12 rounds per minute.
.....10.5 cm leFH 18/40 howitzer = 8.
Shell contains about the same amount of HE filler as a 105mm artillery shell.
285kg weapon weight.
.....10.5 cm leFH 18/40 howitzer = 1,955kg.

The 120mm mortar used by Germany and the Soviet Union looks very impressive on paper. How well did it perform in combat?

 

[Jabberwocky]

There is a very good write up of Finnish experiences with both Soviet 120mm and German 120 mm mortars here

FINNISH ARMY 1918 - 1945: 120 MM MORTARS

 

[davebender]

I'm surprised Germany didn't adopt that solution during 1935 when their army expanded from practically nothing to 36 divisions. It would have been a quick, inexpensive way to provide new infantry divisions with supporting artillery. When artillery production catches up with demand you can add some 10.5cm K18 weapons to each division for long range missions plus some of the heavier 15 cm sFH 18 howitzers.

 

[tomo pauk]

While the 105mm howitzers were a significant leap forward when compared with 75-77mm light guns from ww1, they were all requiring the capable motor towing in order to be efficient - weapon weighted far more, requiring more crew, ammo + charges being notably heavier, piece for piece. 105mm stuff was not able to be manhandled meaningfully, 120mm mortars could be manhandled. The cost of the mortar was indeed negligible when compared with 105mm howitzers.
Interestingly enough, with 120mm mortar at hand, Soviets went for 122mm howitzers.

 

[Shortround6]

The 120mm mortars were a great addition to a units firepower. However with a range of just over 1/2 the range of 105 howitzer they could not provide the deep support for an attack or help with counter battery duties.

 

[davebender]

That's why I suggested inexpensive 120mm mortars for general infantry support plus long range weapons like the 10.5cm K18 for long range missions. You get the best of both worlds. 120mm mortars can be pulled by almost anything. Two horse team, Kettenkraftrad and even the small 4WD VW Schwimmwagen would be adequate for towing a 120mm mortar cross country. Only the long range weapons would require artillery tractors.

How do the mortars compare with 10.5cm howitzers for accuracy and sustained fire ability?

 

[Shortround6]

Sustained fire there probably isn't much to choose. Accuracy of most WW II mortars is pretty bad.

The German 10.5cm howitzers weighed a bit under 2000kg in action, a bit more on the move. The 10.5cm K18 went over 5600kg in action and even more on the move. There were never going to be enough of them, especially considering that the 15cm s FH18 used the same carriage/recoil system. The 10.5cm K18 gun was a corp or army asset, it was not deployed on the divisional level.

A problem with the 12 cm mortars is not the weight of the mortar but in supplying them with ammo. A Russian M1943 mortar weighs about 500kg (1100lbs)on the move. The shells weigh about 35lbs each, bare without shipping containers/boxes. 32 unboxed bombs weigh more than the Mortar on it's wheels. The impact of the 12cm mortar bombs is certainly impressive but you are not going to keep them feed for very long without motor transport. a six tube battery firing 6 bombs per minute (under 1/2 peak rate of fire) for ten minutes will use up 6.3 tons of mortar bombs. Add in the shipping/transport containers and the logistics get real interesting.

 

[Tante Ju]

Mortars are effective for direct support. But have limitations.

However Shortrand point on ammo supply is very good. Also worth considering at what area a 10,5cm with double range can provide fire support immidate compared to a mortar, and how many more mortars you need to cover the same area with equal firepower.

I would say 3-4 times as many mortars (crews, logistics) and deep they cannot support.

 

[davebender]

Since 1914 German infantry have relied on 105mm howitzers firing danger close to defeat enemy attacks. That won't work if 120mm mortar accuracy isn't similiar to 105mm howitzer accuracy.

 

[Shortround6]

A study of the Modern (post 1995) US 120mm mortar. Wartime mortars from both Germany and Soviet union ( and any body elses smooth bores) is not likely to be as good, in fact they could be considerably worse. Mortars at the time were not only viewed as a "cheap" substitute for artillery, their ammunition was viewed as "cheap" to produce too. This lead to cheaper materials and more allowable variations or tolerances than allowed for in Artillery ammunition.

http://www.dtic.mil/ndia/2005smallarms/tuesday/trohanowsky.pdf

 

[psteel]

German infantry given the choice between infantry guns or mortars went for the infantry guns. Not only were they much more accurate, they had much more stopping power when it came to enemy AFV/vehicle assaults. As I recall when the move away from the infantry guns to mortars was proposed by 1943, it was expected to replace each infantry gun with two mortars to make up for the loss of accuracy.

 

[tomo pauk]

When the German Army was given such a choice? In one corner we have the lightest infantry gun (7,5cm), weighting 400 kg, able to propel the 6kg shell, and on the other corner we have the 120mm mortar weighting under 300 kg, mine weighting 2,5 times more, with range being 80% greater. Accuracy and stopping power vs. tanks with a shell fried at 210m/s is nothing to write home about; the traverse of 12deg also hampers firing vs. moving targets. Germans have had another choice, 105mm mortars, weighting 100 kg - 1/4th of the 7,5cm IG, range about the same, shell 20% heavier.

 

[psteel]

The decision to go to 'infantry guns' was done in the late 1920s under the first rearmament drive and there was no modern 120mm mortar for another 10 years.The design for the original german 10cm mortar began in 1934 and ended in 1939 leading to mass producion later that year.

During the war the 120mm mortar was to replace the 150mm infantry gun, the 82mm mortar was to replace the 75mm infantry guns....btw both these guns had HEAT rounds by 1941/42. The 105mm mortar was specifically designed to fire chemical shells and all such weapons were under special units.

Bit of reseach might have helped?

 

[Tante Ju]

Tomo, please for example tell me how you use a mortar to knock off a MG position in street fighting, when MG is on 2 level of 5 level building... just to illustrate in this case a IG is much better solution.

 

[tomo pauk]

Well, sure enough I wouldn't be driving any towed stuff into the street, the MG would've have a live fire exercise with the gun it's crew. So, definitely not a plus for a towed IG.

The decision to go to 'infantry guns' was done in the late 1920s under the first rearmament drive and there was no modern 120mm mortar for another 10 years.

Thanks.
Saying that 'there were no modern' this or that is a moot point; there was no ground breaking technology that would've prevent a design production of 120mm mortars, all the way between the world wars. All what was needed was Heer's requirement.

The design for the original german 10cm mortar began in 1934 and ended in 1939 leading to mass producion later that year.

There you go

During the war the 120mm mortar was to replace the 150mm infantry gun, the 82mm mortar was to replace the 75mm infantry guns....btw both these guns had HEAT rounds by 1941/42. The 105mm mortar was specifically designed to fire chemical shells and all such weapons were under special units.

There was nothing preventing the 105mm firing HE mines, and those were issued anyway. Stating in one sentence 'mass production' and on the other 'all such weapons were under special units' is contradictory.

Bit of reseach might have helped?

Of course, please do some research.

 

[Shortround6]

The small German infantry gun was used in street fighting at times. It was small enough to be pushed into position (around a corner) and had an armored shield. certainly not ideal at one or two block distances but perhaps at longer ranges?

The 1920s and early 30s were a period of ground breaking technology in many fields. Couple this with most armies around the world being way under funded and research and development was in fits and starts, as were tactics.

Most WW I mortars looked like Junior cannon with breech mechanisms, elevating gears and recoil systems.

7.58 cm Minenwerfer - Wikipedia, the free encyclopedia

17 cm mittlerer Minenwerfer - Wikipedia, the free encyclopedia

Mortier de 150 mm T Mle 1917 Fabry - Wikipedia, the free encyclopedia

Or they were a cheap and at times scary lot of equipment.

Stokes mortar - Wikipedia, the free encyclopedia

2 inch Medium Mortar - Wikipedia, the free encyclopedia

14 cm Minenwerfer M 15 - Wikipedia, the free encyclopedia

Some armies were still using the original Stokes in 1930 if not later.

Basic Field Manual. Volume III, Basic Weapons. Part Four, Howitzer Company / prepared under the direction of the Chief of Infantry. :: Obsolete Military Manuals

The German infantry gun offered 3-4 times the range of some of these contraptions and better accuracy. In some cases MUCH better accuracy. The 4 in Stokes mortar ( a chemical weapon) used a Similar design bomb as the 3 inch, basically a flat nosed can with propelling charge on the back. It was fitted with an "all ways" fuse as it tumbled in flight and could not be depended upon to land nose first.

The French Company of Edgar Brandt took the basic Stokes mortar and through a number of improvements brought it up to the WW II standard. Most nations either bought mortars from Brandt or licensed them. Better, more areo dynamic bombs, Stronger barrels of better steel, improved sights and mounts and so on brought the mortar to what it was at the beginning of WW II. Ranges 2-4 times the WW I Stokes and better accuracy although that is saying much. In many cases the cheap approach compromised the actual usefulness of the basic design. Since firing stresses were less cast iron bodies could be used, cheaper but thicker walled (less HE) and did not fragment well. Stamped sheet metal fins sometimes riveted together. Thin fins will work but they are subject to handling damage and the resulting loss of accuracy (British 4.2 in mortar displayed a rather amazing and annoying habit, damaged fins would cause the bomb to tumble in flight but instead of causing random dispersion it caused the bombs to drop about 1000yds short, usually near the forward observer

The also had to be a change in tactics and other changes in technology. Battalion/regimental support weapons existed because in WW I it was too difficult for the battalions/regiments to communicate with Brigade or Division headquarters to ensure heavy weapons (artillery) support whenever wanted/needed. In some cases the request for fire support was received but guns were already committed to supporting a different Battalion/regiment.

the capabilities of the weapons should be matched to the expected areas the unit is expected to cover. A battalion is expected to cover a certain length of frontage in defense and a rather smaller frontage in offence. It is weapons are expected to reach into the enemy area a certain distance. AS you go up in unit size the frontage is multiplied by the number of battalions but the depth of penetration into the enemies territory increases. An infantry battalion has no business trying to silence enemy guns 6-10 kilometers passed the front line even if they are shooting at them. That is a job for Divisional or Corp artillery.

The German guns were actually held at regimental level in a platoon of six and parceled out in pairs as needed or as the unit commanders saw fit. Since each Battalion had at least six 81mm mortars (if up to strength) the addition of a pair of 7.5cm infantry guns must have offered something the mortars couldn't supply.

 

[davebender]

Actually it was done during WWI.

By 1914 the German Army was well down the road towards using indirect fire field howitzers ILO direct fire field guns. During 1915 7.7cm field guns began receiving a new carriage that allowed an elevation up to 40 degrees.

WWI German infantry still desired a few light artillery weapons that could place direct fire on an enemy MG position or other strongpoint so they adopted several different infantry guns. One consisted of a lightened 7.7cm field gun mounted on a new carriage with small wheels so it sat low to the ground. Another infantry gun consisted of captured Russian 7.62mm field guns modified in a similiar manner. There was general agreement that 75mm was the smallest useful HE shell. These direct fire infantry guns did not substitute for indirect fire mortars or howitzers which Germany also had plenty of.

 

[tomo pauk]

The small German infantry gun was used in street fighting at times. It was small enough to be pushed into position (around a corner) and had an armored shield. certainly not ideal at one or two block distances but perhaps at longer ranges?

<......>

The German guns were actually held at regimental level in a platoon of six and parceled out in pairs as needed or as the unit commanders saw fit. Since each Battalion had at least six 81mm mortars (if up to strength) the addition of a pair of 7.5cm infantry guns must have offered something the mortars couldn't supply.

I'll readily admit that mortars are not capable to replace the I.G. in every role 100%.
An 'intermediate' I.G. of maybe 105mm calibre, fitted with muzzle brake, weighting circa 700-800 kg would've been maybe the better solution than going for 7,5cm + 15cm combo; nice punch, yet far less demanding on 'dedicated' prime movers.

 

[psteel]

The guy doesn't understand so no point in wasting any more time on him.

 

[davebender]

ntermediate' I.G. of maybe 105mm calibre, fitted with muzzle brake, weighting circa 700-800 kg would've been maybe the better solution than going for 7,5cm + 15cm combo

Germany began developing the 7.5cm LG40 recoilless rifle during 1937. This weapon entered service during 1941 with a total of 450 produced. During 1942 Germany fielded the 10.5cm LG42 recoilless rifle. These weapons would have replaced existing German direct fire infantry guns but they were overtaken by new technology. Lightweight and dirt cheap Panzerfaust and Panzerschreck began entering service during 1943. These direct fire infantry weapons have nothing to do with mortars which are indirect fire weapons. Different type weapons for different missions.

Large mortars such as the Soviet M1938 overlap with light howitzers to some extent. I'm attempting to determine the extent to which mortars can substitute for howitzers.