Aerial warfare in the Winter War
The aerial warfare in the Winter War was the aerial aspect of the Winter War between Finland and the Soviet Union from 30 November 1939 to 13 March 1940. While the Soviet air forces greatly outnumbered the Finnish Air Force, the Soviet bombing campaign was largely ineffective, and Finnish pilots and antiaircraft gunners inflicted significant losses on the Soviets.
About 2,500 aircraft of the Soviet Air Forces, most commonly the Tupolev SB-2 bomber, supported the Red Army invasion of Finland. The material damage by bomber attacks was slight, as Finland did not offer many valuable targets for strategic bombings. Targets were often small village depots of small value. Finland had only a few modern highways, so the railway systems were the main target for bombers. The rail tracks were cut thousands of times but were easily repaired, and the Finns usually had trains running in a matter of hours.
Finland's capital city, Helsinki, was bombed on the first day of the war but was the target of raids only a few times thereafter. Finland lost only 5 percent of its total man-hour production time due to Soviet bombings. Nevertheless, bombings affected thousands of civilians as the Soviets launched 2,075 bombing attacks on 516 localities. Air raids killed 957 Finnish civilians. The city of Viipuri, a major Soviet objective, was almost leveled by nearly 12,000 bombs.
Finnish Air Force
At the beginning of the war, Finland had a very small air force, with only 114 combat airplanes fit for duty. Therefore, Finnish air missions were very limited and fighter aircraft were mainly used to repel Soviet bombers. Old-fashioned and few in numbers, Finnish aircraft could not offer support to the Finnish ground troops. In spite of aircraft losses throughout the war, the Finnish Air Force grew by 50 percent by the end of the war. Most new aircraft shipments arrived during January 1940.
Finnish fighter pilots often dove into Soviet formations that outnumbered them ten or even twenty times. Finnish fighters shot down 240 confirmed Soviet aircraft, against the Finnish loss of 26. A Finnish forward air base often consisted of only a frozen lake, a windsock, a telephone set and some tents. Air-raid warnings were given by Finnish women organized by the Lotta Svärd. Finnish antiaircraft gunners shot down between 314 to 444 Soviet aircraft. 
At the start of hostilities, the Finnish Air Force had 146 aircraft of all types at its disposal. The primary fighter aircraft were 15 Bristol Bulldog IVs, which had entered service in 1935, and 41 of the more modern Fokker D.XXI. There were also 18 license-built Bristol Blenheim bombers. In 1939, an order had been placed in Italy for 25 Fiat G.50 fighters; two were being assembled in Sweden when the war broke out.
During the war, a number of aircraft were ordered from abroad:
- 30 Gloster Gladiator II biplane fighters from the United Kingdom
- 12 Bristol Blenheim IV bombers from the United Kingdom
- 30 Morane-Saulnier M.S.406 fighters from France
- 44 Brewster 239 fighters from the United States
- 22 Gloster Gauntlet trainers from the United Kingdom
- 10 Fiat G.50 fighters from Italy
In air combat, Finland used the "finger four" formation (four planes split into two pairs, one flying low and the other high, with each plane fighting independently of the others, yet supporting its wingman in combat), which was superior to the Soviet tactic of three fighters flying in a delta formation. This formation and the credo of Finnish pilots to always attack, no matter the odds, contributed to the failure of Soviet bombers to inflict substantial damage against Finnish positions and population centres.
- Trotter 2002, pages 187–193
- Kurenmaa, Pekka; Lentilä, Riitta (2005). "Sodan tappiot". In Leskinen, Jari; Juutilainen, Antti. Jatkosodan pikkujättiläinen (in Finnish) (1st ed.). Werner Söderström Osakeyhtiö. pp. 1150–1162. ISBN 951-0-28690-7.
- Peltonen, Martti (1999). "Ilmasota talvisodassa". In Leskinen, Jari; Juutilainen, Antti. Talvisodan pikkujättiläinen (in Finnish) (1st ed.). Werner Söderström Osakeyhtiö. pp. 606–649. ISBN 951-0-23536-9.
- Trotter, William R. (2002, 2006) . The Winter war: The Russo–Finno War of 1939–40 (5th ed.). New York (Great Britain: London): Workman Publishing Company (Great Britain: Aurum Press). ISBN 1-85410-881-6. "First published in the United States under the title A Frozen Hell: The Russo–Finnish Winter War of 1939–40"