The B-239 was a denavalised version of the F2A-1 Buffalo, ordered by Finland in 1939 as a means of acquiring a modern fighter plane. Unlike the US Navy F2A-1, the plane had better performance due to being stripped of arresting gear and all other equipment necessary for carrier landings, together with a more powerful Wright R-1820-G5 engine producing 10 hp more than the US Navy Buffalos. Another difference was mountings for four machine guns: two in the engine cowling and two in the wings. The planes themselves arrived too late to participate in the Winter War, but were used extensively in the Continuation War all the way to late 1944, when they were withdrawn from service. Finnish pilots regarded the plane as very manoeuvrable, easy to fly, and not requiring extensive maintenance. LeLV 24 had a score of 26:1 using the B-239, as they claimed 477 Soviet planes shot down for a loss of just 19 B-239s.

Introduced in Update "Fire and Ice" in the Swedish air tree, the Finnish B-239 has big potential even in the hands of a not-so-skilled pilot. Its manoeuvrability and armament compared with contemporaries make it a very dangerous foe. The B-239 is best utilised in a role similar to the Bf 109 as a boom-and-zoom fighter, although its ability to turn-fight — not only at high speed — is better than the Messerschmitt’s.