At the beginning of the Winter War, the Finnish Air Force was equipped with only 18 Bristol Blenheim bombers and 46 fighters (32 modern Fokker D.XXIs and 14 obsolete Bristol Bulldogs). There were also 58 liaison aircraft, but 20 of these were only used for messengers. The most modern aircraft in the Finnish arsenal were British-designed and -built Bristol Blenheim bombers. The primary fighter aircraft was the Fokker D.XXI, a cheap but maneuverable design with fabric-covered fuselage and fixed landing gear. On paper, this force should have been no match for the attacking Soviet Red Air Force. However, the Finnish Air Force had already adopted the Finger-four formation in the mid-1930s, which was to be found to be much more effective formation than the Vic formation that many other countries were still using when World War II began.