pThe I-15, I-16 and I-153 fighters were the world's first mass-produced fighters. A total of 17,000 Polikarpov fighters had been manufactured by the time their series production was terminated in 1941. Aircraft of the first series successfully operated in Spain with the Republicans during the civil war 1936-39, in Chinese hands against the Japanese 1937-38, and then with the Soviet Red Air Force again against the Japanese in Mongolia during the Nomonhan Incident 1939. Russian-flown fighter also saw action against the Finns in 1939-40 during the Winter War. ppBy the time the Wehrmacht launched its surprise attack on the USSR on 22 June 1941, more than 20 Soviet pilots had made ace in Polikarpov fighters during these various conflicts. Still more aces were created in the first months of the German invasion, although losses suffered by the Soviet Air Force's five borderline military district units equipped with some 4000 I-15bis, I-153s, and I-16s were astronomical. Despite being thorough