MINE THROWERS & MORTARS

PART 1

Mine throwers and mortars in Finland

 

The early history - enter minenwerfer

Mine thrower was the predecessor of mortars, as we know them today. The history of mine throwers started from Russian - Japanese war of 1904 - 1905. During that war Japanese military not only proved that coastal-mortars suited well for destroying fortifications, but also were the first ones to use weapon, which could be considered a mine thrower. This first mine thrower had a reinforced bamboo tube loaded with small charge of black powder and it was used to fire explosive charges to Russian trenches. Introduction of this weapon was noted also in other countries and inspired the Germans enough to start development work based to this weapon concept. First German mine thrower was introduced in year 1908. When World War 1 started the German military had 44 heavy (250-mm mine) throwers and 166 medium (170-mm) mine throwers in its use. German Army considered its minenwerfer demolition weapons, so they were issued to engineer units. During World War 1 German mine throwers proved extremely successful so their numbers were considerably increased during the war. By the time World War 1 ended German military had issued some 1,200 heavy (180-mm, 240-mm and 250-mm) mine throwers and about 2,400 medium (170-mm) mine throwers. Besides being effective against enemy infantry both heavy and medium mine thrower proved effective also against field works of various types. But still the most numerous of mine throwers in German use during World War 1 proved to be light (76-mm) mine thrower developed only during the war - some 12,400 were manufactured before World War 1 ended. Practically all other counties taking part to World War 1 developed their own mine throwers or at least adopted mine thrower designs developed by their allies.

PICTURE: 91-mm mine thrower GR model 1915 of Miinanheitinyksikkö in Vilppula. (Photo from book Suomen Vapaussota kuvissa, edition of 1934). CLICK THUMBNAIL TO SEE LARGER PIC (124 KB).

During Finnish Civil War in year 1918 few Russian 91-mm mine throwers saw use. Finnish White Army captured four of these mine throwers early on and used them to equip Miinanheitinyksikkö (Mine Thrower Unit). This fought in Vilppula and Ruovesi in February of 1918 and took part in White offensive towards city of Tampere until running out of ammunition. Also Finnish Red Guards may or Russian troops may have used some mine throwers in Finland, but no evidence of this has remained. Still the same year Finland bought 18 German 76-mm mine throwers, which remained in Finnish use until replaced with 81-mm mortars before World War 2.

PICTURE: Photograph showing Finnish soldiers with German 76-mm mine thrower. This photo is from 1920's and taken in Santahamina military base. The soldiers are all wearing M/22 uniforms. Notice wheels of the mine thrower left on the ground and one round on top of the wheel. (Photo owned by Jaeger Platoon Website). CLICK THUMBNAIL TO SEE LARGER PIC (103 KB).

Note: While some English-language sources prefer to call this weapon type trench mortar, the term mine thrower is used in this website for a good reason. The term that the Germans used from their mine throwers was minenwerfer and the Finnish term miinanheittäjä. All these three terms mean literally exactly the same.

 

Stokes trench mortars and Brandt-Stokes mortars

For practical purposes mortar is lighter and simpler weapon based to mine thrower. While the Germans had been the ones to develop first mine throwers the basic design of classic was based to British World War era design. Wilfred Stokes was manager in successful engineering company called Ransomes and Rapier, which had concentrated to farming machinery and steam engines. Year 1915 he started developing trench mortar design of his own. While most mine thrower / trench mortar designs of that time were either light but primitive or useful but heavy the design that Stokes come up was both light and exceptionally effective. His three inch trench mortar consist only three parts still found in most mortars today - barrel, base plate and bipod. The barrel rested on base plate, which took the recoil, and the whole weapon was supported by bipod, which contained elevation adjustment in form of screw elevation gear. Lower end of the barrel was closed and had a fixed firing pin, which fired primer of propellant charge when mortar bomb was dropped to barrel. Mortar bomb was a cylinder shape and made from cast iron. It's rear end hold basic propellant charge - which was packed in a 12-gauge shotgun shell. Original fuse used in bombs was time-delay fuse with delay of nine seconds and based to fuse originally used in Mills bombs (British egg hand grenades). Three-inch Stokes trench mortar went through series of tests and after some improvements it was introduced to use of British Army in August of 1915. It proved exceptionally good weapon so it soon gained popularity among British soldiers and was produced in large numbers before end of World War 1.

Stoked continued developing fuses for mortar shells and introduced also 4-inch version of this trench mortar, which was adopted to use of British Army during the war. While Stokes trench mortars were the best of mine throwers and trench mortars used in World War 1 they still had room for improvement. The biggest problem of Stokes trench mortar was dispersion of shots, which was considered too large. After WW1 development continued with m/1920 and m/1921 Stokes mortars, both of which proved commercially unsuccessful. Finally at 1924 French engineer Edgar William Brandt developed new kind of mortar shell and also improved Stokes mortar. The newly introduced mortar shell had accuracy dispersion of only about 1%, so it was more than satisfactory for the use. This new mortar became known as Stokes-Brandt model 1924-1925 mortar and started selling extremely well. By World War 2 81-mm Brandt-Stokes mortars and their further developments became part of standard weaponry for armies of practically all countries.

 

General Nenonen makes his move

In Finland the new 81-mm Stokes-Brandt mortar attracted attention of Major General Vilho Petteri Nenonen already in year 1924. Thanks to his friend British General Sir. W.M. Kirke and test shooting documents of the mortar Nenonen became interested about Stokes-Brandt mortar. Once he got familiar with it he soon realised that Stokes-Brandt mortar was just what Finnish infantry needed as a support weapon. He organised that two 81-mm mortars and some ammunition were bought and tested at spring and summer of 1926. In these tests 81-mm Brandt-Stokes mortar proved so useful and effective that it confirmed his determination to acquire them for Finnish Army. However, as Stokes-Brandt mortar was such a new weapon many of his fellow officers had doubts concerning its effectiveness. There existed a real danger of of the whole idea ending up being buried in some committee (like happened with so many planned weapons purchases of Finnish Armed Forces at that time). Autumn of 1926 Nenonen got his chance, when he was pointed as substitute for Commander of Finnish Army. He used his substitute position effectively cutting the red tape and personally ordered the purchase of 70 Stokes-Brandt mortars and ammunition. Once these first 81-mm mortars (81 Krh/26) had been introduced to use of Finnish Army they proved a success and resulted several purchases of Tampella-manufactured versions. During the couple of years after that 81-mm Stokes-Brandt mortar become household name among armies all over the world, but thanks to Nenonen Finland became one of the first countries to adopt it.

 

Tampella goes mortars

Finnish Company Tampella also got interested about new 81-mm Stokes-Brandt mortar and even if it had been patented also in Finland, started production of almost direct copy. Tampella named this first mortar it manufactured 81 Krh/32 (81-mm mortar model 1932), but Finnish Army approved it to use with name 81 Krh/33 (81-mm mortar model 1933). Rather surprisingly this breach of patent lead to positive result - year 1934 Brandt-Stokes and Tampella signed mutually beneficial contract. This not only gave Tampella rights for producing Brandt mortars under license, but also made it sub-contractor for "Etablissements Edgar Brandt" (as the French company was known). In other words: Tampella could manufacture Brandt mortars for Finnish military as long as it paid 8% royalty for each mortar. In addition Brandt ordered its own mortar designs from Tampella to armed forces of other countries and sold these Tampella-manufactured mortars as Brandt products. In early 1930's weapon's manufacturing of Tampella was separated as Weapons Department ("Aseosasto") of Tampella. Before Winter War Tampella manufactured Brandt both 81-mm and 60-mm Stokes-Brandt type mortars. Both starting of mortar production in Tampella and likely also reaching this contract with Brandt can be credited to same person - Hans Otto Donner, who's family at the time owned about one third of Tampella. While Hans Otto Donner lacked official standing to Tampella this master of science in engineering and captain of French Army with dual citizenship of both France and Finland had quite a bit of power in Tampella. Between years 1933 - 1939 Finnish Army ordered Tampella 572 81-mm mortars, but only about half of these were delivered before Winter War. During the same period it also manufactured 579 mortars to export. When Winter War begun 30th of November 1939 from these 579 mortars 127 still remained in Finland and were confiscated by Finnish authorities for Finnish Army. Since Brandt had already paid 67 of the confiscated mortars completely and advance payments for the rest of them, it turned out to be quite unhappy about the situation. The resulting argument destroyed what had this far been mutually beneficial arrangement between Tampella and Brandt. Tampella refused to pay the mortars, which Finnish authorities had confiscated, and Brandt continued demanding financial compensation until May of 1942. However it is quite possible that the argument may have had also other contributing factors – in late 1930’s Tampella’s success in developing mortar models of its own started to become quite obvious and the uncomfortable political developments may have affected the opinions among Brandt staff. The demands would have been convenient way for Brandt employees in occupied France to protest after Finland became co-belligerent on German side against Soviet Union in summer of 1941.

PICTURE: Finnish 81 Krh/33 mortar with its crew photographed during Winter War. 81 Krh/33 was the first mortar manufactured by Tampella. (SA-kuva photo archive, photo number 3988). CLICK THUMBNAIL TO SEE LARGER PIC (144 KB).

As mentioned Tampella factory Weapons Department started developing its own mortars in 1930’s. The first own design it manufactured was 81 Krh/35 (as called by Finnish Army, Tampella knew it as 81 Krh/34), which was manufactured with two barrel lengths. It was followed by 81 Krh/38 (in Finnish Army nomenclature, Tampella called it 81 Krh/36/38). Tampella had also started developing its own 120-mm mortar based to Brandt-design quite early on and had manufactured a prototype of its design already in year 1935. The development continued several years after this prototype and when the final production version did not appear until year 1940. 120 Krh/40, as this first mass-produced 120-mm Tampella-mortar was known, was considerably more robust but also heavier weapon than the first prototype and proved excellent weapon during World War 2. Besides 81-mm and 120-mm Tampella designed also some 47-mm mortars, but the project didn’t get beyond field test prototypes. Tampella had manufactured also 60-mm mortars for Brandt before Winter War, but their production ended when Winter War started and they didn't see any real use with Finnish military.

 

Mortars of Finnish Army during Winter War

When Winter War started 30th of November 1939 Finnish Armed Forces were material-wise very poorly equipped – it had serious shortages of weapons and materials of just about every possible kind. Mortars and mortar shells were not exception to this. As mentioned in addition of Tampella continuing production Finnish authorities tried easing this shortage by confiscating all mortars, which Tampella had manufactured for export, and also by acquiring more mortars from abroad. Before Winter War all mortars that Finnish military had used were 81-mm calibre and during the war this proved essential. Tampella had been manufacturing large production series of 60-mm Brandt mortars, so quite a few of these would have been available, but domestic ammunition production did not exist for them. Not to complicate ammunition production Finnish Army decided to acquire only 81-mm from abroad and gained some success in this. As a consequence for all practical purposes during Winter War Finnish Army basically used only 81-mm mortars. Both France (81 Krh/31 and 81 Krh/36) and Italy (81 Krh/36) were willing to provide Finland about 100 81-mm mortars, but only 50 of the French mortars arrived before Winter War ended 13th of March 1940. Sweden (81 Krh/34) and Hungary both delivered Finland smaller batches of 81-mm mortars. France, Hungary, Italy and Sweden all sold Finland also mortar shells for 81-mm mortars during Winter War. Once the war started Tampella had its hands full – manufacturing 81-mm mortars and 37 PstK/36 would have offered work enough, but repairing of damaged weapons demanded even more resources. During World War 2 Tampella repaired captured Soviet mortars, antitank-guns and field artillery pieces (both field guns and howitzers) equipped with spring recuperators up to 122-mm calibre. When also mass-production of 120 Krh/40 mortars started soon after Winter War as a result the production of 81-mm mortars was reduced to minimum.

Mortars captured and lost by Finnish Army during Winter War:

Captured:

pcs:

50-mm

(*) 31

82-mm

(*) 63

Total:

94

Lost:

81-mm

25

(*) Only 15 captured 82-mm mortars and 15 captured 50-mm mortars were issued to Finnish troops by end of this war.

Mortars bought (or some confiscated in case of Tampella) during Winter War:

Source:

pcs:

Tampella

183

France (*)

100

Italy (*)

100

Hungary

16

Sweden (**)

25

Total:

424

(*) The actual number delivered may have been few more or less. It seems that 50 of the French mortars arrived before ending of Winter War but the actual arrival date for Italian mortars still remains mystery.

(**) These seem to have arrived with Swedish-Norwegian volunteer unit SFK (Svenska Frivillig Kåren).

Notice: All these mortars were 81-mm calibre.

 

Mortars of Finnish Army during Continuation War

Year 1941 Finnish Army was using 13 mortar models (smoke throwers not included). Thanks to mortars bought from abroad and captured from the Soviets by summer of year 1941 the number of 81-mm and 82-mm mortars in Finnish use had reached reasonable level. This allowed Tampella to concentrate its remaining capacity of mortar manufacturing in making new 120-mm mortars. Finnish Army had ordered 160 new 120-mm heavy mortars (120 Krh/40) in December of 1939 and after Winter War ended in March of 1940 Tampella could start manufacturing them. These 120 heavy mortars were delivered 1940 – 1941 and the production was continued after the ordered production series had been completed. The total number of 120 Krh/40 delivered to Finnish military 1940 – 1941 was 206. After this came a pause in Finnish orders for 120-mm mortar. When Swedish military was interested about this new heavy mortar, Tampella started manufacturing them for Sweden. By end of World War 2 Tampella delivered Sweden 215 heavy mortars "12 cm GrK m/41" (as Swedish Army called them). The total number of 120 Krh/40, which Tampella delivered to Finnish military by year 1945 was around 356 - 358. During first year of Continuation War Finnish Army captured large number of Soviet mortars and the ones captured intact or in condition good enough to be repaired were reissued to Finnish use. For example the number of 120-mm Soviet mortars captured in 1941 was larger than the number of Tampella-manufactured 120-mm mortars at the time. The increasing number of 120-mm mortars available allowed Finnish Army to double the number of 120-mm mortars in its official table of organisation and equipment (TO&E) in year 1942. Practically this increased number of 120-mm effected the situation in such a way that when year 1941 Finnish regimental mortar company typically had two mortar platoons each with two 120-mm mortars, by 1944 they usually had three mortar platoons each with three 120-mm mortars. During Continuation War Finland was quite self-sufficient in manufacturing mortar shells for 81-mm and 120-mm mortars, only 1941 and 1944 relatively small number of mortar shells were acquired from Germany.

During Continuation War also some new Finnish mortar projects appeared, these included short-barrel 81 Krh/42 that could be carried by one man and super-heavy 300-mm mortar capable destroying fortifications, but neither of these two projects reached mass-production. Another notable Finnish Army project related to mortars was focused in developing wooden turntable designs, which could be used under existing mortars. Finnish Army was basically fighting a trench war from January of 1942 to May of 1944, hence mortars were rarely moved from their well-built mortar pits, in which this sort of rather heavy turntables could be used. They would have allowed already existing mortars to be aimed to any direction in much faster manner. While troops themselves built turn tables for their mortars and Ordnance Department spent considerable effort in developing them, ultimately due to problems caused by sand and snow getting into in between the turntable, none of the designs saw mass-production. Once the Soviets launched their offensive in June of 1944, the trench war ended and so did the immediate need for this sort of design.

PICTURE: 81-mm mortar on turntable in April of 1944. Soldiers are from 3rd Battalion of Infantry Regiment 61, which at that time was stationed in Aunus / Olonets Carelia. (SA-kuva photo archive, photo number 148689). CLICK THUMBNAIL TO SEE LARGER PIC (160 KB).

Mortars bought and captured during Continuation War:

Bought from domestic companies

47-mm - 60-mm

68

81-mm

(*) 118

120-mm

111

Total:

297

Bought from Germany:

120-mm (**)

50

Captured:

50-mm - 60-mm

1312

82-mm

415

107-mm - 120-mm

200

Total:

1927

(*) Numbers given by sources vary, 118 seems to be the most likely number.

(**) These were German-captured Soviet 120-mm mortars

From December of 1941 to June of 1941 the frontlines of Finnish - Soviet front remained the same. This period known as "trench war" period ended when June of 1944 Soviet military launched their massive summer offensive in Finnish front. The offensive started 9th of June in Carelian Isthmus and about week later in River Syväri / Svir. The offensive first forced Finnish use retreat in Carelian Isthmus and north of Lake Laatokka / Ladoga and retreat of this magnitude tends of correspond large losses of heavy weapons. Finnish Army lost quite a large number of mortars during this short period of retreat, but not in alarming scale. Thanks to domestic production of 120 Krh/40, efforts of effective repairs system and newly captured mortars (especially Ilomantsi battle in late July - early August) the losses could be quickly replaced. As the table above indicates Finnish Army remained mortar-wise well stocked until end of Continuation War.

Most important mortars in use of

Finnish Army:

81-mm

82-mm

120-mm

Date:

30th of Nov 1939

292

0

0

13th of March 1940

(*) 691

(**) 15

1

1st of July 1941

911

?

162

1st of June 1944

848

460

430

1st of Sept 1944

677

502

438

(*) Probable number based to calculations, the numbers found from several sources vary between 666 and 788.

(**) 63 had been captured, but Finnish military had issued only 15 of them at that time.

 

PICTURE: Captured Soviet 120 Krh/38 mortar with Finnish crew. Photo taken in area of River Syväri / Svir November of 1942. (SA-kuva photo archive, photo number 114239). CLICK THUMBNAIL TO SEE LARGER PIC (162 KB).

Finnish mortar ammunition during World War 2

In case of mortars the actual weapon is just part of the weapons system, for which the other equally or even more important part is ammunition. One could claim for a good reason that during World War 2 Finnish inventory of 81-mm mortars was very mixed with mortars of this calibre acquired from various countries, but this was nothing compared to the variety of 81-mm mortar shell used. Finnish mortars manual from year 1941 lists 16 mortar shell models of this calibre manufactured in Britain, Finland, France, Germany, Hungary, Italy, Poland and Sweden in use. This large variety was mostly caused by ammunition shortage suffered during Winter War. At that time during Winter War Finnish domestic mortar shell production capacity was too small and as with artillery ammunition shortage of fuses the actual deliveries even further. Finnish industry manufactured blanks for 81-mm mortar shells by casting them while blanks for 120-mm mortar shells were pressed. During Continuation War every now and then limited of 81-mm mortars was disturbed by shortages of percussion caps and celluloid plates, but otherwise domestic mortar ammunition production had reached such high level it could keep Finnish Army provided. In fact from 1942 to1944 excess production capacity allowed even selling of 120-mm mortar ammunition to Sweden. Percussion caps were needed for cartridge cases of primary propellant charges and celluloid plate for manufacturing of additional propellant charges. During World War 2 Finnish industry manufactured about 4.9 million 81-mm mortar shells, about one million 120-mm mortar shells and some 5.4 million fuses for mortar shells.

 

Use of mortars in Finnish Army

Starting from the beginning Finnish Army considered mortars to be infantry support weapons, which were used by infantry formations. During World War 2 the only exception to this was short-lived Mortar Artillery Battalion 1 (Kranaatinheitinpatteristo 1) that existed in late part of year 1941. What is known this unit created from personnel of field artillery and armed with captured Soviet 120-mm mortars proved quite successful, but it was abolished for reasons of organisational integrity. For Winter War (1939 - 1940) Finnish Army issued the 81-mm mortars that it had to regimental level - those infantry regiments lucky enough to be equipped early on each received company of four 81-mm mortars. The infantry regiments equipped later had no such luck - if they were lucky they could receive captured 82-mm mortars or had to do without. When Continuation War (1941 - 1944) started the situation was different - now each battalion received platoon of three mortars 81-mm or 82-mm mortars and platoon of either 81-mm or new 120-mm mortars were issued to regimental level. Once production of 120-mm mortars picked pace, they replaced in 81-mm mortars in these regimental mortar platoons. Finally as the number of both domestically manufactured and captured 120-mm mortars increased regimental mortar platoon was replaced with mortar company, which by end of the war usually had nine 120-mm mortars.

Mortars of Finnish Army, 1st of June 1944:

47-mm (*)

50-mm

81-mm

82-mm

120 Krh/38

120 Krh/40

Where:

issued to troops:

19

407

546

69

122

201

army depots:

32

586

58

115

0

0

storages of military districts:

0

18

(**) 196

196

0

22

military schools / training centres:

0

0

0

76

56

15

elsewhere (under repair etc):

0

214

48

4

9

5

Total:

51

1225

848

460

187

243

(*) These were Finnish 47 Krh/41 mortars.

(**) 51 mortars among these lacked mortar directors.

 

After the war

As typical with Finnish Army weaponry for political reasons the situation did not develop during late 1940's and early 1950's. The uncertainty concerning interpretation of Paris Peace Treaty of 1947 stopped the development for several years. Finnish Army repaired much of the mortars damaged or worn during the war and scrapped the ones repairing which wasn't practical, but there was no new development or new orders to Tampella beyond completing the ones ordered during the war. Once the war ended the number large percentage of mortars demanded repairs - most of them had served several years in hard conditions and were now dangerously worn. Because of this Finnish industry needed to organise several repair programs for them. While ending of Continuation War almost immediately halted practically whole Finnish weapons manufacturing for couple of years Weapons Department of Tampella was an exception to this. Its leadership decided to continue manufacturing previously ordered mortars even if General Headquarters of Finnish Armed Forces had cancelled rest of the wartime orders in autumn of 1944. Due to this unlike large majority of Finnish industry Tampella continued manufacturing weapons until 1945 when it delivered last of the mortars ordered during the war. After this Tampella mortar manufacturing stopped and the factory capacity was converted for manufacturing civilian products. For second half of 1940's Weapons Department of Tampella concentrated manufacturing tools such as rock drills. Tampella restarted mortar and mortar ammunition development around year 1950.

Late 1950's Finnish military declared obsolete all 47-mm and 50-mm mortars. Year 1960 most of them were sold with some mixed 81-mm mortars, 81-mm smoke throwers and 120-mm smoke throwers to Interarmco, which exported them. Rest of the World War 2 era mortars remained in Finnish Army use and were modernised in post-war era. Finnish Defence Forces first kept them in use and then warehoused until year 1986, when some of the WW2-era 81-mm mortar models (all 81 Krh/32, all 81 Krh/33 and 42 mixed modernised mortars) were declared obsolete. Much of the Finnish wartime mortars, which were modernised after it, have remained warehoused to this day. This is not as surprising as some might think - after World War 2 the world-wide development of mortars have concentrated more in developing their ammunition and fuses instead of developing the actual mortars. Recently Finnish Defence Forces have started scrapping their older heavy weapons due to reduction of troops and new weaponry (such as AMOS mortar system) replacing the old ones. This scrapping of old heavy weaponry includes also much of the older mortar models still warehoused. Year 1991 Tampella weapons manufacturing was merged with Vammaskoski Works (which belonged to Finnish Ministry of Defence) and the new resulting company was named Vammas. Vammaskoski Works in Tyrvää (some 50 km from city of Tampere where Tampella was based) had started as a small army depot in year 1943. Since 1950's Vammaskoski Works in addition to its main products (tractor excavators and road graders) had manufactured also 55 S 55 recoilless rifles and repaired field artillery pieces. Around 1994 - 1995 main Finnish defence materials manufacturers (Lapua, Sisu Defence, Vihtavuori, Finnavitec) were merged with Vammas to create a larger company - Patria Industries. Nowadays the mortar-manufacturing part of this company is Patria Vammas Oy and its latest products are AMOS and NEMO mortar systems.

 


Source materials used for making these mortar pages listed on bottom of MINETHROWERS AND MORTARS PART 7.

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Last updated 11th of August 2013
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