Engineers (Finnish Defence Forces)

Swedish rule

The earliest record of Finnish military engineering was crossing the river Lech in 1632 during the Battle of Rain. Finnish troops would perform engineering tasks in several other wars during Swedish rule.^[5]

Jäger Movement

During the First World War, almost 1,900 Finnish men went to Germany to receive military training as part of the Jäger Movement. Out of the volunteers was formed the 27th Jäger Battalion.^[6]

An engineer company was formed in the Lockstedter Lager [fi; de] training unit on 28 August 1915.^[5] Their training involved various engineer skills, such as fortification, mining, makeshift bridges, and pontoons, in addition to infantry training. When the battalion was formed in May 1916 and sent to the front, the engineer company was 249 strong, 217 of whom were Finnish. When the battalion went to the front on the Misa river, the engineers were designated as the reserve, and worked on building fortifications. Watery conditions, disease, and problems with food supply made conditions miserable.^[6]

On 22 July 1916 the engineers received a movement order, and the next day they, excluding the German non-commissioned officers and 32 Finns, marched to the Riga–Jelgava Railway and were transported to the Schlamp station, from where they moved to encamp at Sale. The next evening the engineers moved to the rally point where they were divided into the infantry squads, 2-3 men per one, of the Reserve Jäger Battalion 1. The attack began at midnight, with the engineers' acting commander lieutenant Basse staying behind. The engineers successfully reached the Russian positions at Smārde (German: Schmarden) and captured five enemies. The Finns received praise from the Germans, including General Wyneken. Two Finns, Paavo Kinnunen [fi] and Matti Fält [fi], died as a result of the battle.^[6] The battle was the so-called Jäger engineers' (jääkäripioneeri) babtism by fire, and became known as the Battle of Schmarden. Its anniversary is celebrated as the branch's anniversary day.^[5]

The engineers returned to near Smārde on 14 August 1916 to conduct building and forest clearing work. As the German engineers had previously thought the work to be too dangerous, the Finns gained a reputation for courage, which resulted in better food supply reliability.^[6]

The battalion moved to the coast of the Gulf of Riga in late August, and the engineers did missions deemed communal or dangerous. The engineers did construction, including the fortification of a base called Laus, destruction of visual barriers, and supported patrols.^[6]

The battalion moved to Liepāja for training and preparations for a return to Finland in March 1917. Most of the company spend the spring and early summer on an engineer course, with many Finns from other companies also participating. Some engineers also participated in other specialized courses. The engineer company had 152 men when the majority of Finns returned to Finland 25 February 1918. The jägers dispersed to various units on return. Less engineers were sent to the Altona-Barenfeld work detachment, meaning they received less diciplinary punishments, and more received the Jäger Memorial Badge, i.e. served honourably, than on average.^[6]

Early independence

During the Finnish Civil War engineers on both sides focused mostly on the destruction and repair or railways, especially railway bridges. There was not much engineer activity, as many Jäger engineers commanded infantry due to the lack of experienced soldiers.^{[7]: 87–88}

Early doctrine was mainly based on German and French ones.^[8] The building of fortifications was held as an important among Finnish engineers, and it was trained up to the beginning of the Winter War.^{[9]: 45–46}

Engineer Battalion 1 was founded at Koria on 9 December 1920.^[5]

The Technical Troops Command was formed in 1921, following the French model,^[10] under which Engineers was also designated.^[11] According to Santeri Sohlman, this unification of command was as much a strategic decision, as a way of cutting on costs.^[12]: 65 Under it Engineer and Signals officers had the same base training, and would often work in units belonging to both branches during their careers.^{[7]: 109–110}

The Technical Troops were disbanded on 30 April 1927, with its commander becoming the Inspector of Technical and Logistics Troops, who lead the branch specific training and equipping of Logistics and the Erillinen hyökkäysvaunukomppania [fi] tank company in addition to Engineers and Signals.^[12]: 40

The Inspector of Technical and Logistics Troops became the Technical Inspector of the Defence Forces in 1933, with the Engineer and Signal units of all branches of the Defence Forces coming under his control, and the War Technical School (Sotateknillinen koulu) for technical troops was founded.^[12]: 48 For the existence in various forms of technical troops, they were led by Engineer trained officer Unio Sarlin.^[12]: 67 Separate Engineer and Signals sections were formed on 4 October 1939, as centralized command of Engineer troops was needed for maximizing the efficiency of fortification works.^[12]: 68

In the 1920s, with divisions included two engineer companies, with separate engineer units for use of higher command.^[9]: 45 Engineer skills focused on building fortifications, water crossings,^[8] and the maintenance of roadways.^[9]: 45

The creation of engineer battalions, three companies, for divisions, with special road maintenance units for corps was decided before the Winter War but was not implemented before it began.^{[9]: 46, 174}

Coming into the 1930s, engineers were still focused supporting movement in line with the attack focused spirit of the Finnish Army at the time.^[9]: 174 During the decade the focus formed around movement support and counter-mobility.^[8] Mining also started became its own thing, and anti-tank work became more emphasized towards the end of the decade. However counter-mobility tactics were not integrated into unit training until the very end of the decade.^[9]: 46 The development of Iivari's quick bridge enabled infantry to perform small water crossing on their own, enabling engineers to focus on larger crossings.^[9]: 46

The Gas Protection School (Kaasusuojelukoulu) was founded in Vyborg in 1933.^[5] The need for protection against battle gases was well accounted for in the wartime structure of units.^[9]: 181

The Winter War

Finnish equipment during the Winter War was inadequate, with only 5,000 anti-tank mines,^[9]: 46 leading to improvised mines being used.^[8]

Although there were suspicions of use of chemical weapons by Soviet troops in December 1939, tests were inconclusive, and consensus by the end of the war was that none were used.^[9]: 181

Engineer troops were often poorly utilized during the war, even used as infantry, as the lack of field exercises before the war caused problems with branch co-operation.^[9]: 174 The value of engineers became clear to infantry leadership during the Winter War,^[5][8] as the value anti-tank work cleared the idea that engineers would just build the infantry's fighting positions.^[9]: 174

Temporary anti-tank troops were often formed from engineer troops by division commands.^[9]: 143

Structural changes were made September 1940. Special units were officially designated independent, as had been practice during the war. The manpower involved in the command of engineer troops was also increased both on the division and corps level. Both experienced further expansions in 1943.^{[9]: 174–175} Engineer troops were increased and gained mechanical equipment, and co-operation with other branches was developed.^[8]

As fortifications had proved to be a great preventer of losses and a leveler of the equipment disparity between Finland and the Soviet Union, it was emphasized and leadership was transferred from the engineer leadership to directly Mannerheim with Edvard Hanell [fi] responsible.^[9]: 175

The Continuation War

During the offensive phase of the Continuation War engineers focused on mobility operations, with frontline troops clearing enemy mines and facilitating water crossings. Rear troops fixed roads and bridges.^[9]: 175

During the slow phase engineers had responsibility for fortifying the front. The deep counter-mobility (syvä suluttaminen) skill was developed during this time.^[5] Focus was on the maintenance of obstacles and the expansion and maintenance of roadways^[9]: 176

During the retreat phase of the Karelian offensive in the summer of 1944, engineers were responsible for destroying routes in order to slow the Soviet advance,^[5] and helping friendly mobility. After the Soviet assault was stopped, counter-mobility and road work became important.^[9]: 176

As the need for combat engineers capable of clearing dugouts became clear during the Winter War, Walter Horn in autumn 1940 and Eero-Eetu Saarinen [fi] in February 1941, were sent to observe German combat engineer training. Germany did not allow more Finnish participation till April 1942 when 28 engineer officers participated on a specially held course.^[9]: 175

Combat engineers as a training branch was started, and training began in June 1941, although it was cut short by the beginning of hostilities. During the war combat engineer roles, such as strike groups and flamethrower use, was formalized on various unit levels.^[9]: 175

Due to the lack of CBRNe threats, CBRNe troops focused on tasks such as disinfection, pest termination,^[5] and fire fighting. The use of covering smoke was also designated to CBRNe. Engineers also used smoke grenades and boxes during assaults.^[9]: 182

The Lapland War

Due to the prevalence of rivers and German obstacles, there was a large amount of engineer troops assigned to the III Corps during the Lapland War. Engineers focused on clearing counter-mobility measures and repairing destroyed roads and bridges.^[9]: 176

Post-war

After the end of hostilities with the Soviet Union, demining operations both inside Finland and the ceded territories began.^[9]: 176

The Keuruu Engineer Regiment [fi] was founded in 1967.^[13]

Deep counter-mobility was codified in the 1960s and the three stages of barrier readiness^[5], III: barrier planned and prepared with reserved materials, II: barrier mostly executed with passage possible at limited points, I: barrier fully executed with no passage possible,^[14] were defined in the 1980s.^[5]

CBRNe was folded into the engineers in 1991.^[8]

Involvement in international operations since the 1990s has helped develop competence in the branch.^[8]

Post 2000

Finland joined the Ottawa Treaty banning anti-personnel mines (AP mines) in 2012, and destroyed last of the banned mines in 2015.^[15] Former head of the Department of Strategy at the National Defence University of Finland, Heikki Hult, has spoken that AP mines are the most important part of infantry warfare, and that the ban is unnecessary as Finnish mines are always well documented. In contrast, Chief of Operations, Jari Kallio [fi], has said that other systems have effectively filled the void left by AP mines, except for the psychological effect of mine terror.^[16]

Finnish troops from the Keuruu Engineer Regiment performed risk assessments and oversight during the destruction of Syria's chemical weapons.^[17] They began their work in December 2013 and returned to Finland in July 2014. 18 professional and reserve soldiers were involved in the operation.^[18]

The Keuruu Engineer Regiment was disbanded on 31 December 2014.^[13]

Chief of Defence Janne Jaakkola spoke on the need of re-evaluating Finland's participation in the Ottowa Treaty based on the mass use of infantry by Russia in the invasion of Ukraine, in October 2026.^[19] Following this, a civic initiative was submitted and gained the required signatures, and the Finnish Government started considering withdrawal.^[20] The parliament voted in favor of withdrawal on 19 June 2025,^[21] and it came into effect on 10 January 2026.^[22] The training and preparation of acquisitions started on the same day, ^[23][24] with directional charges beginning to be trained as mines using tripwires, and newly designed Finnish made mines planned to begin use in 2027.^[25][26]