The Finnish Pioneer Arm

in the Winter War

Part II

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 pioneer arm, as the rest of the Finnish Army, suffered heavily from the tight shoestring budget of the prewar years.

The production of AT-mines had just started in 1939, and only 5 000 mines model m/36 were available at the start of the mobilization. The production was so slow that another solution had to be found. A separate office, called "AT-Mine Office" ("hyökkäysvaunumiinatoimisto" in Fin) was established in the Defense Ministry to address this issue. Their answer was the m/S-39 mine, designed by a team lead by Major Arvo Saloranta (see Finnish AT-weapons -part 2). The wooden-cased mine entered production on 8 November 1939. As military explosives were on short supply, an explosive mix was used in the mines made from chlorate powder and resin (kloraattijauhe & hartsi in Finnish). The wooden casings were produced by furniture factories in Lahti and Helylä. The casings were then sent to special "mine charging depots" ("miinalataamo" in Finnish) that had been established in Lohja, Kouvola and Enso. The "mine charging depots" were very crude indeed, and the work was done mostly by hand and despite the risks involved, no accidents occurred.

According to the book "Talvisodan puolustusministeri kertoo"("The Defense Minister of the Winter War reports"), by J. Niukkanen, page 177, the troops received the following quantities of wooden m/S-39 mines:

As was mentioned before, the shortage of factory produced mines forced the Finnish pioneers to fabricate themselves mines. When doing so, the "Demolitions Regulations" included drawings as an example of their structure. I've added below two types of wooden mines, or improvised AP-mines, which were common among the Finnish pioneers.

	The picture on the left is cutaway from a wooden mine using a percussion fuse. 1. The explosive charge, attached to the cover of the mine (charge 1 - 5 kg) 2. A detonating cord running from the percussion fuse to the explosive charge of the mine 3. The "safety rod", i.e. a stick that went through the mine and prevented the cover from pushing the fuse down. Had to be pulled off from the side to arm the mine. 4. The percussion fuse attached to a piece of wood The safety pin of the fuse was connected to the side of the mine and when pressure is applied to the cover, the cover pushes the fuse down, which in turn pulls the safety pin off the fuse. The top view shows the wire from the percussion fuse coming out through a hole in the cover (1) and attached to the side of the mine. A small gap was left around the cover, it being some 0.5 cm (2) at the front edge of the mine. If the wood was dry, more space had to be left in case the wood gets wet and thus swells. The safety rod had a some steel wire fastened to it (3), to ease the removing of the rod. After the safety rod was removed, the cover was held up by two copper wires (4) attached to the side of the mine. Source: " Hävitysohjesääntö", p.130
	This is a cutaway from a wooden mine using an electric cap. 1. The explosive charge 2. The electric cap 3. A battery 4. Wire connected to small metal plates 5. The safety rod After the rod was removed, the cover was held in place by thin copper wires (visible next to the rod, as in the percussion fuse wooden mine above). As someone stepped on the mine, or a vehicle drove over it, the copper wires snapped, the cover was pressed down connecting the circuit, detonating the electric cap. Source: "Hävitysohjesääntö", p.132
	This is a cutaway from the basic m/S-39, manufactured in the mine charging depots. 1. The explosive charge 2. The fuse 3. The safety rod

 

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Percussion fuses

The basic fuse used in the mines (both factory produced and those fabricated by the troops) was the percussion fuse.

This is a cutaway of the basic percussion fuse. The marked components are 1. The striking pin 2. The percussion cap 3. The spring 4. Sealing screw (keeps dirt out of the "flash tube") 5. The "flash tube", i.e. the flame from the percussion cap travels through this tube and ignites the detonating cord or priming wire attached to the fuse. 6. Attachment hooks (to ease attachment, don't have any role in the function of the fuse) 7. The "safety pin". Note that in the upper figure, the fuse is not "primed", the striking pin has not been drawn "up", into ready position. The lower figure shows the striking pin "ready". The structure of the fuse consists of two parts, the "attachment part"(1) ("kiinnitysosa" in Finnish), and "cap part"(2) ("nalliosa" in Finnish). The fuse on the lower figure on the left has a "joint tube" fastened to the fuse, having the end of either a detonating cord or a priming wire in it. Source: "Hävitysohjesääntö", p.31

Due to the shortage of percussion fuses, the Finnish Army started to manufacture ad hoc percussion fuses, utilizing empty 7.62 mm cartridge cases. The result was a workable but very sensitive fuse. Thousands were manufactured. The cartridge case (1) had inside it a percussion cap (2) and a striking pin with a spring (3). A small rod (4) secured the safety pin (5). Once the fuse was in place, the rod was extracted using the steel wire attached to it (6).

 

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Pioneers in Action

 

When looking at the Winter War as a whole, the pioneers had two main tasks:

1. To build and repair field fortifications and obstacles

2. To lay minefields & improvised AP-mines

In addition to these two, the pioneers performed a wide range of other duties.
- They demolished bridges, buildings & railroads

- In the early phases of the war, they slowed the enemy advance by creating improvised (AP and AT) mines with whatever materials were available

- There was often a pioneer (or pioneers) with the patrols, that were sent to the Red Army rear areas. They were the ones who placed charges on bridges far behind enemy lines after making long journeys through the wilderness accompanied by regular infantry or Sissi's. (These patrols were frequently used on the front ranging from Lake Ladoga to the Arctic Sea. On the Karelian Isthmus, where it was harder to infiltrate enemy lines, these recon and/or hit & run patrols were more rare.)

- When the Red Army artillery was battering the concrete bunkers of the Mannerheim Line, it was often the pioneers who were called upon to do their best to repair the damages during the nights.

- The pioneer companies were often ordered to form "close defense" units (AT-platoons or squads armed with Molotov cocktails and/or satchel charges. E.g. the 10th Pioneer Company, attached to the 5th Division defending Summa, knocked out 10 Soviet tanks in a single day)

- The pioneers themselves fabricated a major portion of the mines and satchel charges used to defeat Soviet tanks.

- Pioneers were used to keep supply routes open, plow roads, build auxiliary roads and cut cracks in the ice of lakes.

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The Trap at Lemetti Village

Source:
Saarinen, Eero-Eetu "Pioneeriaselajin Historia 1918-1968", p196-197

The most unique and probably the most destructive road mining of the Winter War was organized by the 13th Division Engineer Commander, Captain L. Tarkka, on the road running from Kitilä to Uomaa.

The 26th Pioneer Company, led by 2nd Lt. L. Manninen, charged the bridge crossing the Koirinoja stream on the eastern edge of the small village of Lemetti for demolition on 9 December. In addition, the road was mined on a length of 2.5 km to the east. The work was done by two platoons, the 2nd and 3rd Platoons.
Charges ranging from 25 to 30 kg were buried in the road at about 50-meter interval and electrically primed them. The power plant of the village supplied the required power and the total amount of explosives used being about 1 200 kg.

The advancing Soviet forces, which were caught in the trap were elements of the 18th Rifle Division under the command of Brigade Commander G. F. Kondrashov. The trap proved to be very effective.
A Russian POW stated later in an interrogation that the road was filled with men and vehicles and that the losses, in dead and wounded, amounted some 700 men (Source: "Pioneeriaselajin historia 1918-1968" p.197 , citing "The Winter War, experiences of the troops", a memorandum of General Major U. B. Sarlin (The Army Engineer Commander in the Finnish General Headquarters)).

I found in the Finnish War Archives (File ID: SArk, spk, 2575) the records of the 26th Pioneer Company (or "War Diary", "Sotapäiväkirja" as it is called in Finnish). I have added below a map that shows the location of the Lemetti village in Finland and the places mentioned in the records. I have tried to translate the text as accurately as possible. Any comments in (parentheses) are mine, intended to clarify the meaning and to help you understand the text.

War Diary, 26th Engineer Company 9 December 1st platoon constructing abatis' and demolishing communications (networks) between Lake Lavajärvi and Lemetti (village). 2nd platoon constructing booby traps and mining in the Lemetti village and preparing targets for demolition on the road between Ruhtinaanmäki (hill) and Lake Ruokojärvi. 3rd platoon 6 squads mining and constructing improvised AP-mines between the Lemetti village and the Lemetti crossroad. 1 squad constructing (improvised AP-)mines at the company billeting area.   9 Dec - 10 Dec 18.00 - 06.00 hrs Charged (for demolition) 2.5 km of road east of the Lemetti village, ignition (electric power) provided by the Lemetti power plant / 1,2 tons of explosives.   11 December 1000 hrs Fighting commenced in the forward posts near "small Lemetti" ("Small Lemetti" is the farm house a few kilometers southeast from the Lemetti village along the road, visible in the large map below) 1330 hrs The forward guard squad had withdrawn and the battle in Lemetti (village) began. The bridge crossing the stream was first crossed by 3 Russkies. They were shot. At the very moment came more Russkies filling the road, noise of tank engines was heard and 2 (tanks) got to the opening. At that point the road was blown up and immediately after that the bridge. The road was probably filled by infantry columns and tanks / charges were between app. 50 meter intervals / 25 - 30 kg per charge. I assume (the person who wrote the records) the destruction was considerable. One tank had crossed the bridge but it drove into a mine in the Lemetti opening. The demolition squad, under command of Sergeant Pärepalo, disengaged and went straight ahead to Mitro (village), while Platoon Varma (means one of the platoons of the company, whose platoon leaders' last name was Varma) stayed last and mined the road Lemetti village - Lemetti crossroad - Mitro / returned in the evening without casualties.   (The writer was indeed correct in his assumptions, as a Russian POW stated later in an interrogation that the road was filled with men and vehicles and that the losses, in dead and wounded, amounted some 700 men. Source: "The Winter War, experiences of the troops", a memorandum of General Major U. B. Sarlin (The Army Engineer Commander in the Finnish General Headquarters) )   War Diary, 26th Engineer Company, 3rd Platoon 9 - 10 Dec Charged, together with the 2nd platoon, the road east from Lemetti village on an about 2 km stretch. In the afternoon the platoon continued to construct booby traps and lay mines in the Lemetti crossroad and making mines. This is a larger map of the area discussed in the 26th Pioneer Company records. The large white area in the upper part of the map is the Lemetti village. The white areas show the village opening and the cultivated fields cut into the forests. The light purple areas represent farmyards. The black dots represent buildings. If a building is out of an "farmyard perimeter" (i.e. not inside a light purple box), its a shed, barn or other nonresidential building. The "x" next to the village bridge, marks the place of the village power plant, the water mill. The "Small Lemetti" is the farm house located a few kilometers southeast along the road from the village. The thick brown line represents the road. The thin brown lines are trails and small roads. Note that the map displays all "forests" with the same green color regardless of dominating tree type, density etc. The contour lines represent intervals of 5 meters each. I've added to some lines the height above sea level. The blue line is the stream called "River Koirinoja". The darker areas are marshes, again all marked with the same color regardless of marsh type, size, if it had trees or not etc. The map was made according a 1:20 000 map surveyed in 1932. The map shows approximately 3 kms of road from the village towards the border. The road was mined from the bridge to area near the "Small Lemetti" farm.

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The 8th Pioneer Company at Lake Kuolemajärvi
In January 1940

The following is an excerpt from the War diary of the 8th Pioneer Company, found in the "Pioneeriaselajin historia 1918-1968", p.188

This table gives a good indication what the pioneers' did after sunset. The Soviet artillery bombardment wrecked the mine fields, and new mines had to be laid. Note that the 8th Pioneer Company made up 50 % of the pioneer strength of the 4th Division, which in turn defended a front some 20 km wide. And in almost a month, they laid app. 3 500 mines. The "vast minefields" or "millions of mines" so often mentioned when talked about the Mannerheim Line was a myth.

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Finnish pioneers in Suomussalmi

In the withdrawal phase, the Er.P 15 had the 9.Er.Pion.J (9th separate pioneer platoon) attached. When the bulk of Er.P 16 was moved into the area, from Dec 6th onwards, it brought along it's own pioneer asset, 8.Er.Pion.J. In the area was also 13.TieSillanRK (13th Road&bridge building company). The Finnish Pioneer Arm included 4 such companies.
In the beginning of the war, the only pioneer platoon (9.Er.Pion.J) was very busy blowing up bridges, and mining the roads (the mines were all made by the troops, at this point no factory produced mines could be spared to this direction).

When the Finnish GHQ ordered reinforcements from the 9th division into the area (which were formed into the brigade), the force included also pioneer units. First arrived the 17.Pion.K (17th Pioneer company), first elements arriving on Dec 11th, and later on the PionTP 2 (Pioneer replacement battalion 2, consisted of two replacement companies) from Dec 23rd onwards. These two units were formed on Dec 31st into the Pion.P 9 (Pioneer battalion 9).
The Finns brought also into the area the Rask.Aur.Os.6 (Heavy plowing detachment 6, 3 such units were mobilized). This unit arrived after the building of the ice road (in the southern flank of the 44th division) had already begun.

The 17.Pion.K HQ was located south of the Haukiperä ferry, near the HQ of Group Siilasvuo. Two platoons were immediately assigned to the troops operating against the Suomussalmi parish, and the Raate road, while the one platoon (3rd platoon) was sent to secure the Suomussalmi - Ylinäljänkä road. For the duration of the Suomussalmi battle, the platoons operated more or less in different directions, making the concentrated command nearly impossible.

 

I Platoon, 17. Pion.K

The first order of the 1st platoon, led by 2nd Lt. Erkki Lankinen, was to perform AT-duties in the Suomussalmi parish on Dec 13th. The pioneers, armed with 5 kg satchel charges, moved towards the parish, and took positions in a slope of a small hill, in a place where the trees were virtually touching the road. Soon three tanks approached with infantry cover. The tanks opened fire into the woods, and then drove past the Finns. No attempts to destroy the tanks were made as it was nearly impossible to get close to the tanks without being noticed. The tanks stopped near the front-line, and started firing, blindly, tracers into the woods, while the Soviet artillery fired a barrage into the woods.
As the tanks returned into the parish, the again drove past the pioneers. Two squads were ordered to make linked mines (daisy chains), the construction overseen by Sergeant Korja, who also hid next to the road with the mines. The effort was futile because at the moment when Sergeant Korja pushed the mines to the road (probably linked, and attached to a long stick), the tanks stopped and opened fire, forcing the Finns to withdraw.

After a few days, the platoon received an order to erect a minefield in the SE side of the parish, near the Kaleva lodging-house. 12 mines, made by the troops, were laid, the work being hindered by occasional fire from the concrete basement of the lodging-house, where the Soviet troops had made a fortified position.

The 1st platoon took also part in the final assaults against the Soviet troops in the Suomussalmi parish. They fought mostly as regular infantry, but as they had more satchel charges than the rest of the troops, they proved valuable in clearing some of the most resilient positions.
After the fight in the parish was over, the 1st platoon spent few days in clearing the area, sorting out captured material and silencing the last point of resistance, which was in the sauna of the Suomussalmi parsonage. The Russians surrendered only after the door was opened with a crowbar and two hand grenades were thrown in.

 

II Platoon, 17.Pion.K

The II platoon, led by 2nd Lt. Osmo Eskola (total of around 50 men, 2 horses, 16 rifles and 1 pistol) was assigned to the Os.Kontula, which was to take the isthmus between Lake Kuomasjärvi and Lake Kuivasjärvi. The detachment advanced unopposed to the River Kuomasjoki (a rather narrow "river" connecting the lakes), and the pioneers immediately dismantled the bridge, cut down the telephone poles and severing the lines.
About two hours after the bridge was taken apart, at dusk, a column of trucks, escorted by an armored car arrived from the east. The pioneers opened fire with their rifles with the result that armored car opened fire, providing covering fire while the trucks turned around and withdrew. The armored car failed to do the same. As it tried to turn, it became stuck, and the crew abandoned it. The pioneers couldn't prevent the crew from escaping, as the they had from the beginning of the engagement had only 10 rounds per rifle, and they were already nearly out of ammo. Behind the abandoned armored car was one car with flat tires.

In the morning, the result of the engagement was checked. There were some blood in the snow, and in the ditch near the armored car was a binocular and a map pouch. The armored car was inspected, and it was noted that it had been immobilized by a lucky shot. A bullet had stuck between the break shoe and the brake band, locking the steering. After a quick repair, the armored car was again in perfect condition, and it was driven to the Finnish side. The pioneers removed the DP from the armored car, and took it into use, as they did with the rifle inside the armored car. The car (with the flat tires) was also brought behind the lines, but it was left unused.

Later that night arrived ammunition replacements and the first mine. Wire entanglements were erected to both sides of the road (on the eastern side of the river), and the only mine was buried after thorough consideration of the exact location.

The next morning, the platoon dug itself foxholes, and erected improvised AP-mines (hanging explosives in the lower branches of trees that could be blown up by pulling the wire from the Finnish side).

A lull of few days followed after which a tank approached the platoon's positions, and luckily the tank drove directly into the only mine, severing the track and jamming the turret. But as the turret pointed directly towards the Finnish positions, the crew started to fire all weapons against the Finns. Two men panicked and vanished (the other one returned that same evening, and the other was found 8 days later wandering in the woods). Two men left to flank the bridge area, and closed in on the tank from the side. The first attempt was a failure, as the explosive charge, that was attached to the gun barrel, was too small. Another try was a success, as two satchel charges were placed on the deck. After the explosion, the barrel pointed upwards and the tank was silent.

The platoon was still suffering from a serious shortage of rifles, but it was soon handled when a Border Guard sergeant approached the pioneers and asked for assistance. A patrol had hijacked two trucks loaded with weapons a few km east. Before the trucks were sent to the Finnish rear, every man was armed.

Later on, the pioneer platoon (which had been defending the isthmus alone) received reinforcements, as the threat of the 44th division grew. And after the two light field guns arrived (into direct fire positions, to act as AT-guns), the situation was safe enough so that the billeting area could be relocated 1 km behind the defense positions, near the Palovaara hill (or more like a rise). There was a shortage of tents, but the problem wasn't that severe as most of the men were either in the defensive positions or reinforcing patrols. Before December ended, the platoon received a new supply of mines ( 5 AT-mines!!!).

When the JR 27 launched it's attack against the Suomussalmi parish, part of the platoon was sent to start constructing the ice road into the flank of the 44th division. Straws from a barn nearby were used to strengthen the ice

III Platoon, 17.Pion.K

The 3rd platoon, led by 2nd Lt. Aappo Laitinen, was sent via Puolanka and Joukokylä to Näljänkä by trucks (a 120 km trip), where they spent the night. The next morning, the pioneer platoon, accompanied with an infantry half-platoon and a mg-squad (1 machine gun). The distance to Suomussalmi was some 60 km, and there were no Finnish units ahead of them.

In the evening, the force arrived to a place called Vääkkiö, where they established an field outpost. The next day was spent preparing the road for withdrawal (an abates was erected on the road, wire entanglements were made to both sides of the barrier, and the small bridge over the river Junnojoki was charged. After the night, further preparations were made along the road behind Vääkkiö (some 11 km from Ylinäljänkä towards Vääkkiö), where another abatis was made.
During this time, enemy forces approached the Finnish outpost twice, both times stopping at the abates. The next patrol was accompanied with a tank, but the effort to destroy it failed.

After the PPP 6 arrived to Vääkkiö, one squad, led by Corporal Kaikkonen, was assigned to the Group Susi. The rest of the pioneer platoon joined the PPP 6 in the advance towards Suomussalmi. After the PPP 6's drive stopped in the isthmus between lakes Alajärvi and Kovajärvi, the pioneer platoon was located to a small village of Löytölä, from where it launched in the following days many patrols, erecting abatis and sowing minefields (at this point it's probable that the Finns feared a large scale attack, as abatis were erected behind the isthmus-line behind the PPP 6. Before Christmas, the platoon was ordered to blow up the bridge crossing the river running through the isthmus. A three man team, led by Ensign Karppinen, started to crawl towards the bridge (there were Soviet troops entrenched on the other side), pulling 50 kg of explosives with the, which were placed on skis. Even while there was a Soviet sentry, near the bridge, the team managed to charge the bridge, and attached the wire (which was also pulled with the men) to the explosives. The men ran to the river bank, on the Finnish side and yelled "vetäkää" ("pull" in English). The fusing worked well, and the explosion rendered the bridge useless.

The pioneer platoon took part (with the bulk of it's forces) in two patrols to the Suomussalmi - Peranka road. One pioneer squad took part in an attack made by the 1./PPP 6 (1st company, 6th Bicycle battalion) on Dec 27th, where the squad laid mines in Kuurtola. Between Dec 29th and 30th, the pioneer platoon was assigned to a patrol, led by Lt.Kousa, which was formed around a rifle platoon. The platoon made an abates, and laid improvised AP/AT mines. While in work, the the infantry section covering the work, ambushed two Soviet patrols, each having about 10 men, annihilating both.

After the fight in Suomussalmi was over, the platoon was ordered to dismantle all barriers, clear the minefields, and repair the roads and bridges. It took a few days to accomplish this, and on New Years Day, the platoon returned to it's parent company, which was now formed into a Pioneer battalion.

The sole squad, which was assigned to Group Susi, was occupied in sowing mines and erecting abatis all around the operative area of Group Susi. The squad returned back to it's parent platoon on January 20th.

Go to Part I