A colour photograph of Bf-109 E-3a fighters of the Royal Yugoslav Army Air Force. These were delivered in 1939, though some were delivered without any weapons being installed. Yugoslavia received 75 aircraft and had 61 on strength in April 1941 (when Germany invaded) but they were mostly destroyed on the ground by preemptive Luftwaffe airstrikes that heralded the invasion, code-named “Operation Punishment”. The few survivors were handed to the air forces of Romania, Bulgaria and the newly-formed Independent State of Croatia.