The Finnish Pioneer Arm

in the Winter War

Part I

In Part I

• The Birth of the Pioneer Arm

• The state of the Pioneer Arm before the Winter War
      Training
      The Finnish GHQ order, 21 October, establishing training priorities during mobilization

• The mobilization
      The organization of the Pioneer Arm High Command during the Winter War (figure)
      Different unit types and the number of pioneer units raised
      Different pioneer unit types and their strengths

• The Pioneer Company
      The organization of a Pioneer Company

• Other supporting Pioneer units

• Wartime Allocation of Pioneer Troops
      The allocation of Pioneer units on 14 December 1939 (table)
         The Pioneer units under the command of the GHQ Pioneer Commander, and in the C-in-C's reserves on 14 December 1939 (table)
         Pioneer units in the Isthmus Army on 14 December 1939 (table)
         Pioneer units on the eastern front ranging from the Lake Ladoga to Lapland, on 14 December 1939 (table)

• Changes during the war
      Total number of Pioneer units in the Pioneer Arm, mid January
      New units formed during the war (table)
      Personnel strength of the Pioneer Arm at mid-January 1940 as reported by units to the GHQ
         Pioneer units in the Isthmus Army (Kan.A), 13 March 1940 (table)
         Pioneer units on the eastern front ranging from the Lake Ladoga to Lapland, 13 March 1940 (table)
  

 

In Part II

• Equipment
      Most widely used mines and improvised AP (antipersonnel) mines during the Winter War (table)
      Consumption of Pioneer Material
      Improvised AP/AT-mines, or "wooden mines"
         Percussion fuses

• Pioneers in Action
      The Trap at Lemetti Village
      The 8th Pioneer Company at Lake Kuolemajärvi, in January
      Finnish Pioneers in Suomussalmi

The roots of the modern Finnish pioneers lies in the German-trained 27th Jaeger Battalion (during World War I). The battalion had, in addition to the four Jaeger companies, one MG-company and one artillery section, a pioneer company. The founding day of the company was 28 August 1915, when the Imperial order raising the battalion, was given.

In the beginning nearly all of the men in the pioneer company were Germans (all officers and NCO's were Germans, as was the majority of the privates). There was only one platoon of Finns, 31 men to be exact. The number rose considerably as more and more volunteers arrived at the Lockstedt training center. The total number of Finns, who served in the pioneer company reached 343 men. Some of the Jaegers rose in rank, and when the company finally left the training center for the Russian Front in May 1916, the ratio of Germans and Finns was 32 - 217. At that time, the highest ranking Finn was K. R. W. Mandelin, who was a "senior platoon leader" (Oberzugführer), and was the 2nd in command.

When the 27th Imperial Jaeger Battalion was formally disbanded on February 13th 1918, the Finnish Jaegers formally swore the military oath to the new legal government of Finland.

Many of these Jaeger pioneers became the trained core of the pioneer arm in the Finnish Army and made a career, some serving for well over a quarter of a century in the Finnish Army (men like U. B. Sarlin, K. E. Pylkkänen, H. Uimonen, L. I. Kumlin, O. Bonsdorff, to name a few).

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The State of the Pioneer Arm before the Winter War

Training

In the 1930s, the Finnish pioneer training was handled by the Pioneer battalion ("Pioneeripataljoona", May 8th 1919 - October 10th 1939, located in Koria), and by the separate pioneer company ("Erillinen Pioneerkomppania", August 1st 1927 - September 27th 1939, located first in Koria and from May 1928 onwards in Kellomäki near Terijoki).

The pioneer battalion (four companies) was responsible for training conscripts to serve as regular pioneers. The battalion also had an NCO training school that trained all the pioneer NCOs of the Army. The battalion was, from 1925 onwards, also responsible for exercising the pioneer reserves (officers, NCOs and men).

The separate pioneer company also trained regular pioneers, but with an emphasis on demolitions. From 1937 onwards, the task of the company was to train the men of the infantry pioneer units. The NCOs were sent to the pioneer battalion for NCO training.

As usual, the Civic Guard played an important role in keeping up the pioneer skills of the pioneer reserve. And when the mobilization was ordered, eighteen pioneer companies were raised in different Civic Guard districts.

It took a long time before the pioneers got their first field regulations. Only in the early 1930s, were the first regulations published. The first one was the "Field Construction Regulation II, Technical Part" ("Kenttätyöohjesääntö II Teknillinen osa" in Fin) in 1931 and the "Pontoon Regulations I" ("Ponttooniohjesääntö I" in Fin) in 1932. Then there was a long pause before any new regulations were published (in fact no new regulations were published before the outbreak of the Winter War). This handicap was luckily offset by a small number of books that dealt with different issues of the pioneer arm. These had been published in the 1920s and 30s, such as "Fortifying" ("Linnoitustaito" in Fin) by J. C. Fabritius in 1921, "Fortifying of Positions and Field Fortifications" ("Asemien linnoittaminen ja kenttälinnoitustyöt" in Fin) in 1922, "Explosive Substances"("Räjähdysaineoppi" in Fin) by J. Wuorinen in 1928.

The overall skill level of the Finnish pioneers was not as good as it should have on the eve of the war. Between 1932 - 1934, the mobilization system was changed to one based on regional mobilization. This resulted in there not being enough trained pioneers in the districts that were supposed to raise pioneer units. Therefore, a large number of men assigned to pioneer units had not received pioneer training. This had been noticed time and again, but despite repeated reports, no significant progress had been made to correct this problem.

During the mobilization, there were some pioneer companies which had only 45 - 47 % of trained pioneers. The situation was even worse in some of the special units, like the tool depot detachments or pontoon columns, which had sometimes only a few pioneer-trained men.

While the time between the start of the mobilization and the outbreak of war (five to seven weeks) was crucial for strengthening the defensive positions and acquiring material, it was extremely important to the pioneers as this time would give them the opportunity to teach their untrained men basic pioneer skills.

A very notable thing, when talking about prewar training, is the low level of attention that mines and booby traps received. Before the Winter War, mines were not regarded as an important part of pioneer training. No regulations or instructions on how to employ mines even existed until the eve of the Winter War. The primary AT-mine in the prewar years, the m/36 (see Finnish AT-weapons -part 2) was kept so secret that only a few of the career officers had ever seen or heard of it. (After the Winter War, mines & mining were considered to be a very important part of the work of the pioneers). There was a "Demolition Regulation" ("Hävitysohjesääntö" in Finnish) published in late 1938, where there were instructions for making mines and booby traps. Of course it takes a long time before new regulations are adopted, especially in a reservist-based army. Just before the war, on October 15th 1939, a small 9-page pamphlet titled "Operating Directions for AT-Mines" ("Hv.miinojen käyttöohje", written by Lt.Col H. Uimonen, in Fin) was published.

Due to the low number of factory-produced AT-mines, land mine warfare training started with the troops manufacturing mines for themselves. Also the "rail charges" were produced by the troops for use against railroads and their employment was practiced.

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The Finnish GHQ issued an order on 21 October 1939 that established the following training priorities:

1. The use of AT-mines in creating road blocks
- efficient placement of mines (for officers)
- ordering of where the mines should be placed
- laying and camouflaging of mines
- dummy minefields
- the mapping of minefields (for officers, who were responsible for producing a detailed map of the emplaced minefield)
2. The use of AT-mines in minefields (off-road)
- efficient placement of mines (for officers)
- ordering of where the mines should be placed
- laying and camouflaging of mines
- laying of mines in pairs
- the mapping of minefields (for officers, who were responsible for producing a detailed map of the emplaced minefield)
3. The placing of booby-traps (meaning antipersonnel mines)
- in wire obstacles
- in minefields
- in tree barriers / abatis
- in buildings
4. Demolition of roads
- demolition of culverts
- using "pre-chambered road crater"
5. Demolition of railroad
- using "rail charges" ("kiskopanosside" in Finnish, see *? This note seems to be missing below)
- actions of the demolition team
6. Demolition of bridges
- the demolition of different types of bridges
- setting the charges quickly (if the situation demands)
- "charging partly" (i.e. using only a part of the calculated quantity of explosives needed to destroy the bridge)
- "total charging" (i.e. using the full calculated quantity of explosives to destroy the bridge)
7. Building a field bridge

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The Mobilization

During October, the different military areas (or districts) raised the planned pioneer units. Those pioneer units that were a part of the covering forces deployed on the Karelian Isthmus had already been raised in September.

 

The organization of the Pioneer Arm High Command during the Winter War

As the chart shows, the Pioneer Commander, Major General Unio Sarlin, in the General Headquarters (hereafter GHQ in the text), was directly under the command of the Commander-in-Chief of the Finnish Army, Marshall Mannerheim. He was directly responsible for the supply of the pioneer arm, all fortification tasks and the general operation of the pioneer units. He was assisted in the GHQ by his personal aid, Lt.Col Pylkkänen.

Directly under his supervision were two offices. The Pioneers office ("Pioneeritoimisto" in Finnish), Pion.kom.1, which handled the use of the pioneer units, pioneer branch training and the development of new methods and equipment, based on wartime experience. This office also introduced to the Pioneer Commander all issues concerning the quantity and quality of new equipment,that was to be purchased.

The actual purchasing of new material was handled by the Pioneer Equipment Office, attached via the technical office to the Defense Ministry.

The other office, directly under the command of the Pioneer Commander, was the Fortifications Office ("Linnoitustoimisto" in Finnish), which was divided into two separate offices: the Planning Office ("Suunnittelutoimisto" in Finnish), Pion.kom.2, and the Construction Office ("Rakennustoimisto" in Finnish), Pion.kom.3. The Fortifications Office was responsible for general planning, allocation of resources and funding the fortifying works.

Every operational-level unit (meaning army, corps, division or separate battle groups (like "Group Talvela")) had a pioneer commander with the headquarters staff. He commanded all of the pioneer units in the subordinate units and was responsible for pioneer equipment supply.

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Different unit types, and the number of pioneer units that were raised during the mobilization:
(Source: "Pioneeriaselajin historia 1918 - 1968", p.170)

- 29 pioneer companies
- 2 separate pioneer companies
- 1 motorized pioneer company
- 11 separate pioneer platoons
- 1 separate motorized pioneer platoon
- 1 separate motorized pontoon battalion
- 4 road & bridge building companies ("tien- ja sillanrakennuskomppaniaa" in Finnish)
- 2 road building companies ("tienrakennuskomppaniaa" in Finnish)
- 6 road repair companies ("tienkorjauskomppaniaa" in Finnish)
- 10 pontoon columns ("ponttoonisiltakuormastoa" in Finnish)
- 3 heavy plowing detachments ("raskasta aurausosastoa" in Finnish)
- 3 pioneer equipment depot detachments ("pioneerivarasto-osastoa" in Finnish)
- 8 tool depot detachments ("työasevarasto-osastoa" in Finnish)
- the Vyborg labor battalion ("Viipurin työpataljoona" in Finnish)
- 1 Pioneer replacement regiment ("Pioneeritäydennysrykmentti" in Finnish)

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Different pioneer unit types, and their strengths
(Source: "Pioneeriaselajin historia 1918 - 1968", p.156 - 157)

The basic Finnish pioneer unit was the pioneer company. The organizational structure of the pioneer companies was the same as it had been in the early 1930s. The companies were rather large units, having a large supply train. This was due to the design of the pioneer platoons, which were intended to be able to operate independently, each having its own delivery squad attached. It was quickly noticed during the war that this type of pioneer companies were too cumbersome. The companies were slow-moving and the absence of a headquarters made it difficult for the company commander to lead the unit efficiently.

The Organization of a Pioneer Company
The TOE strength was 5 + 31 + 211 = total personnel 247
(meaning 5 officers, 31 NCO and 211 men)

The company commander had a deputy commander Delivery platoon 0+7+19 7 NCO, 19 men, had 10 horse-drawn vehicles (explosives carriage, tamper carriage, 3 bridge construction carriages, equipment carriage, feed carriage, field kitchen, food carriage, kitchen equipment carriage, field workshop carriage) Pioneer platoon 1+8+64 Platoon leader + deputy leader 7 pioneer squads 1 delivery squad pioneer squad 1 + 8 delivery squad 0 + 8 6 horse-drawn vehicles (tool-, explosives-, 3 bridge construction-, food-, feed carriage) The total number of horses in the company was some 100

 

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Other Supporting Pioneer Units
(The pioneer companies, separate platoons (and later battalions) were the "fighting units" of the pioneer arm)

 

The Finnish Pioneer Arm had three different types of companies for the construction and repair of roads. These were the road building companies, road and railroad building companies and road repair companies. The differences between these companies were mainly in the vehicles. They all were more or less occupied during the Winter War with one task: plowing the roads (therefore it was common to call all of these units "road companies"). There were also the specialized plowing detachments, which were formed to concentrate the few purpose-built vehicles and trained personnel.
The pontoon columns, which naturally did not have much to do after the rivers froze up, stored their pontoons, and were used for transportation duties.
The Vyborg labor battalion (this designation changed on March 3rd 1940 to Vyborg Pioneer battalion) was formed in Vyborg, mainly for use in various bridge-building duties. It was attached to the II Corps and spent most of the war building field fortifications behind the Main Defense Line.

In the prewar plans, the Finnish Isthmus Army headquarters did not have any organic pioneer units under it's direct control (i.e. under the direct control of the Army pioneer commander). This was changed during the mobilization and some pioneer units were placed under the direct control of Colonel V. H. Vainio, the pioneer commander of the Isthmus Army. To help Col. Vainio in his duty, a pioneer office was established under his command.

In every corps and division two pioneer companies were placed under the command of the pioneer commander, as ordered by the TO&E (table of organization and equipment).

* = was formed on 10 December, from the 1st, 2nd and 3rd separate pioneer platoons, that had been part of the covering troops
** = while the U-Group had in fact ceased to exist (the Red Army troops were already reached the Mannerheim Line), officially the Group still existed (at least on paper) and Capt Tuurna was the pioneer commander until 18 Dec 1939.

To ease centralized control, make the pioneer companies lighter (by reducing the number of vehicles), and to establish a headquarters to help the commander, the pioneer companies were formed into pioneer battalions in some of the front-line divisions. Already in 1938 - 1939, a proposal to change from two pioneer companies per division to a battalion organization had been made. It was accepted, but the mobilization began before it could be implemented. The three divisions that were formed during the war, had a pioneer battalion instead of two separate pioneer companies.

Every separate battalion ("Erillinen Pataljoona", "Er.P" in Fin), most of which were deployed along the long Finnish eastern front, which ranged from Lake Ladoga to the Arctic Ocean, had a separate pioneer platoon attached to it.

- 6 Pioneer battalions
- 23 Pioneer companies
- 2 motorized pioneer companies
- 2 separate pioneer companies*

* = 1.Sep.Pion.K was formed from separate pioneer platoons, which had been a part of the Covering Troops, 2.Sep.Pion.K was formed by the Border Guards

GHQ -pion.com's = Pioneer companies under direct command of the Pioneer Commander in the General Headquarters
Isthmus Army = Pioneer units in the Isthmus Army
IV Corps = Pioneer units in the IV Corps
Group Talvela = Pioneer units in the Group Talvela
P-SR = Pioneer units in the North Finland Group
LR = Pioneer units in the Lapland Group
Pion.P 21 & 23 = Pioneer battalions, which were at that moment a part of the Home Front troops (C-in-C's strategic reserve)

Go to Part II