Several nations, including Finland, Belgium, Britain and the Netherlands, ordered the Buffalo. The Finns were the most successful with their Buffalos, flying them in combat against early Soviet fighters with excellent results.During the Continuation War of 1941–1944, the B-239s (a de-navalized F2A-1) operated by the Finnish Air Forceproved capable of engaging and destroying most types of Soviet fighter aircraft operating against Finland at that time and achieving in the first phase of that conflict 32 Soviet aircraft shot down for every B-239 lost, and producing 36 Buffalo "aces".
In December 1941, Buffalos operated by both British Commonwealth (B-339E) and Dutch (B-339D) air forces in South East Asia suffered severe losses in combat against the Japanese Navy's Mitsubishi A6M Zero and the Japanese Army's Nakajima Ki-43 "Oscar". The British attempted to lighten their Buffalos by removing ammunition and fuel and installing lighter guns to improve performance, but it made little difference. After the first few engagements, the Dutch halved the fuel and ammunition load in the wing, which allowed their Buffalos (and their Hurricanes) to stay with the Oscars in turns.