Chief Marshal of Aviation Alexander Novikov led the VVS from 1942 to the end of the war, and was credited with introducing several innovations and weapons systems. For the last year of the war German military and civilians retreating towards Berlin were hounded by the presence of "low flying aircraft" strafing and bombing them, an activity in which even the ancient Polikarpov Po-2, a much produced flight training "(uchebnyy)" biplane of 1920s design, took part. However, this was but a small measure of the experience the "Wehrmacht" were receiving due to the sophistication and superiority of the Red Air Force. In one strategic operation alone, the Yassy-Kishinev Strategic Offensive, the 5th and 17th Air Armys and the Black Sea Fleet Naval Aviation aircraft achieved a 3.3 to 1 superiority in aircraft over Luftflotte 4 and the Royal Romanian Air Force, allowing almost complete freedom from air harassment for the ground troops of the 2nd and 3rd Ukrainian Fronts.