A line of defensive fortifications extending across the Karelian Isthmus from the Gulf of Finland to Lake Ladoga, the Mannerheim Line was named for Carl Gustav Emil von Mannerheim, the Finnish military commander and president who, as chairman of the Finnish defense council, advocated construction of the line and oversaw its construction.
The Mannerheim Line was intended to defend against a Soviet invasion of Finland, and it was here that the most intense fighting of the Russo-Finnish War (Winter War) took place in 1939.
The Mannerheim Line was first planned after the Finnish civil war, which followed the conclusion of World War I. Construction began in the 1920s and continued throughout the 1930s. When completed, the fortification line consisted of approximately 200 machine-gun emplacements encased in concrete bunkers. The Mannerheim Line was incomplete by the outbreak of the Russo- Finnish War but proved effective nonetheless.
The great advantage of the Mannerheim Line over the more extensive and more famous Maginot Line built by the French along their border with Germany was in its use of the natural terrain to leverage the effectiveness of its defenses. Whereas the Maginot Line and other traditional line fortifications used massive bunkers and other artificial structures, the Mannerheim Line exploited such landscape features as boulders and fallen trees. Whereas the Maginot Line was exceedingly conspicuous, the Mannerheim Line was skillfully camouflaged and thus a far more effective defensive position.
Although superior Red Army numbers eventually forced the surrender of Finland, the Mannerheim Line defenses stalled the Soviet advance for two very bloody months. Embarrassed by the cost of the invasion of Finland, Soviet commanders and politicians greatly exaggerated the extent and construction of the Mannerheim Line, as if to suggest that it was virtually impregnable. It was, in fact, for the most part a series of trenches and common field fortifications punctuated at considerable intervals by more substantial bunkers. Machine guns were the weapon of choice. The Mannerheim Line had virtually no artillery positions. Skillful defense by Finnish troops, not impregnable military architecture, was responsible for the effectiveness of the Mannerheim Line.
The Soviet-Finnish conflict in the winter of 1939-1940, mostly over strategically important territories of the Karelian Isthmus. The air operations demonstrated the abilities and constraints of airpower in action in severe weather and over difficult and heavily wooded terrain. At the outbreak of hostilities, the Soviet air force had assembled about 900 aircraft, expecting an easy and quick campaign. Then Finnish air force had 162 mostly obsolete aircraft of all types.
Enjoying permanent air superiority in the course of the war, the Red Air Force was able to secure vulnerable rear areas from air strikes but failed to eliminate in a surprise strike the dispersed Finnish combat aircraft on the ground. Soviet airpower was engaged primarily in close support, air cover, and airlifting of assaulting troops in the Karelian Isthmus, some limited air operations in the Arctic area, as well as bombing raids on more than 160 rear targets.
Despite large-scale employment of bombers in daytime and clear-weather raids, the Soviets were unable to undermine Finnish defenses, economic life, supply traffic, and morale. This was due to wintertime navigation problems, bombing inaccuracy, and the fierce Finnish air defense, which claimed 275-314 Soviet air losses (more than half of them bombers).
The Finns also used fighters energetically and adapted to winter conditions: They equipped fighters with skis for takeoffs and landings on ice and snow. Their pilots demonstrated a higher level of combat skills compared to the Russian pilots. During the war, Finland received 240 aircraft of all types as well as volunteer pilots from Western countries, but massive aid was compromised by politics and logistical difficulties.
The Soviets massed reinforcements (1,500-2,000 planes) in January-February 1940 and introduced some operational and tactical changes (nighttime and poor-weather bombing raids as well as fighter escorts). Nevertheless, the war was won by the Soviets mostly on the ground due to the dramatic disparity of forces involved. Moreover, the evident failure of the Soviet air campaign was one of the primary reasons the war went on for as long as it did. The total Russian war losses were 594 aircraft; the Finnish air force lost 62 planes from all causes.
Finnish Air Force (in Russo-Finnish Wars)
Seeds of tradition were sown in the Ilmailuvoimat (the Finnish Air Force) during the Winter War (30 November 1939-12 March 1940) against the Soviet Union. Finnish air operations hit their stride during the Continuation War, so called because it continued the conflict begun by the Soviets in 1939. The first real combat for the Ilmailuvoimat occurred during the Soviet invasion of Finland. In this war, the Finns scored 190 confirmed kills and more than 100 probables. They achieved a 16:1 ratio with the Soviets-in aerial combat, the Finns shot down 16 Soviets for every one of theirs the Soviets downed.
The small and ill-equipped Ilmailuvoimat followed certain principals to ensure success. First, by concentrating its fighter power and using the element of surprise, it achieved temporary air superiority. Second, it flew in small, flexible formations. Next, it demanded that its pilots be skilled in aerobatics and combat maneuvers. Finally, Finnish pilots were continuously trained until they were masters in shooting accuracy.
Although Finland did not share the Nazi political ideology, it still formed an alliance with Germany to defend itself against the Soviet Union. When Hitler invaded the Soviet Union on 22 June 1941, Finland went to war. The air force began the Continuation War with 120 fighters (Brewsters, Fiats, Curtisses, Morane-Saulniers, and Hurricanes) and 58 mostly obsolete reconnaissance planes.
Initially, the Finns were quite successful against the Soviets, achieving a 32:1 exchange ratio. As the war went on, the Finnish forces became less effective despite the acquisition of limited numbers of German Messerschmitt Bf 109Gs and Junkers Ju 88s.
The Battle of the Gulf of Finland is the best example of air operations during the war. The Finnish fighter pilots were successful, attaining an average exchange ratio of 25:1. Their strategy of focusing on aerial combat made the difference; raids on Soviet air bases were not worth the risk. The Soviets had no shortage of aircraft but lacked experienced pilots. By focusing on eliminating these trained Soviet pilots, the Finns achieved air superiority.
The Soviets did not wish to spend what was necessary to defeat the Finns militarily, so on 4 September 1944 a peace agreement was signed. The Ilmailuvoimat again finished a war with more fighters than it started with. Finland ended with the largest proportion of aces in the world in relation to population. Most of the Finn aces survived the war.
Further reading: Chew, Allen F. The White Death: The Epic of the Soviet-Finnish Winter War. East Lansing: Michigan State University Press, 2002; Engle, Eloise, and Lauri Paananen. The Winter War: The Soviet Attack on Finland 1939-1940. Mechanicsburg, Pa.: Stackpole, 1992; Trotter, William R. The Winter War, the Russo- Finnish War of 1939-40. London: Aurum Press, 2003. Engle, Eloise, and Lauri Paanen. The Winter War: The Russo-Finnish Conflict, 1939-1940. New York: Charles Scribner’s Sons, 1990. Luukanen, Eino. Fighter over Finland: The Memoirs of a Fighter Pilot. London: Macdonald, 1963. Nikunen, Lieutenant General (ret.) Heikki. The Finnish Air Force (FAF): A Historical Review. Helsinki: Finnish Air Force, 1993.