The Soviet I-153 biplane fighter, also known as “Chaika,” was created in 1938 by the Polikarpov Design Bureau. It was an advancement of the I-15 fighter line, featuring retractable landing gear (unlike the fixed gear of the I-15), and was considered one of the most advanced biplane fighters of its time. A total of 3,437 of these aircraft were produced. The I-153 was first used in combat against Japanese aviation in the skies over Mongolia in the summer of 1939. However, by the time the war between Germany and the Soviet Union began, this fighter was already considered obsolete—its low speed made it unable to catch up with even some bomber modifications like the Ju 88 and Dornier. Despite this, it continued to be used as a fighter, an air defense aircraft, and even as an attack aircraft. During Operation Barbarossa, advancing German forces captured a large number of operational aircraft on Soviet airfields, including the I-153. These were used by the Luftwaffe for test flights, and some were subsequently transferred to Germany’s allies, including Finland.