The Army of the Isthmus was a formation of the Finnish Army during the Winter War

Winter War

The Winter War was a military conflict between the Soviet Union and Finland. It began with a Soviet offensive on 30 November 1939 – three months after the start of World War II and the Soviet invasion of Poland – and ended on 13 March 1940 with the Moscow Peace Treaty...

. It was stationed on the Karelian Isthmus

Karelian Isthmus

The Karelian Isthmus is the approximately 45–110 km wide stretch of land, situated between the Gulf of Finland and Lake Ladoga in northwestern Russia, to the north of the River Neva . Its northwestern boundary is the relatively narrow area between the Bay of Vyborg and Lake Ladoga...

 and was the largest formation of the Finnish Army, as it was charged to defend the important isthmus.

Organisation

The army was organized into two corps. At the beginning of the war it had one division in reserve. Along the Soviet border four delaying groups of smaller units was deployed.

• II Corps
  Finnish II Corps (Winter War)
  The II Corps was a unit of the Finnish Army during the Winter War.The II Corps with the III Corps formed the Army of the Isthmus...
  
   (II AK) under Lieutenant General Harald Öhquist
  Harald Öhquist
  Harald Öhquist was a Finnish Lieutenant General during the World War II.Öhquist joined the Jaeger Movement in 1915 and trained and fought in the Royal Prussian 27th Jäger Battalion. During the Finnish Civil War he was promoted as Major, and Öhquist lead the White Guard battalion in the battle of...
  
  
  • 4th Division
    Finnish 4th Division (Winter War)
    The 4th Division was a unit of the Finnish Army during the Winter War. It was part of the II Corps which fought on the Karelian Isthmus. The 4th Division was responsible for the front between the Gulf of Finland and Viipuri. r- Commanders :...
    
    
  • 5th Division
  • 11th Division (later the 2nd Division)
  • Cavalry Brigade

• III Corps
  Finnish III Corps (Winter War)
  The III Corps was a unit of the Finnish Army during the Winter War. The III Corps with the II Corps formed the Army of the Isthmus . For most of the war it defended the Mannerheim Line on the northern side of the River Vuoksi against Soviet attacks.-Order of battle:*8th Division *10th Division...
  
   (III AK) under Major General
  Major General
  Major general or major-general is a military rank used in many countries. It is derived from the older rank of sergeant major general. A major general is a high-ranking officer, normally subordinate to the rank of lieutenant general and senior to the ranks of brigadier and brigadier general...
  
   Erik Heinrichs
  Erik Heinrichs
  Axel Erik Heinrichs was a Finnish military general. He was also a recipient of the Knight's Cross of the Iron Cross...
  
  .
  • 8th Division
  • 10th Division (later the 7th Division)

• Reserve
  • 1st Division

Immediately by the border on the isthmus were the four delaying groups named after their location:

• U-Group at Uusikirkko
• M-Group at Muolaa
• L-Group
  L-group
  In mathematics, L-group may refer to the following groups:* The Langlands dual, LG, of a reductive algebraic group G* A group in L-theory, L...
  
   at Lipola
• R-Group at Rautu

On February 25 the II Corps was split and a new I Corps

Finnish I Corps (Winter War)

The I Corps was a formation of the Finnish Army during the Winter War. It was formed on February 25 from parts of the II Corps which had become too large to function properly. It fought during the final stages of the war on the front north of Viipuri....

 was established. It was given the 1st and 2nd Divisions (former 11th Division).

Commanders

• Lieutenant General Hugo Österman (until 19 February 1940)
• Lieutenant General Erik Heinrichs
  Erik Heinrichs
  Axel Erik Heinrichs was a Finnish military general. He was also a recipient of the Knight's Cross of the Iron Cross...
  
   (after 19 February 1940)

See also

• Finnish Army (1939)
• List of Finnish corps in the Winter War
• List of Finnish divisions in the Winter War