On April 6, 1941, "Luftwaffe" units in Bulgaria and Romania attacked Yugoslavia during the Bombing of Belgrade. Equipped with a combination of obsolete equipment and new aircraft still being introduced into service, the VVKJ was forced to defend the country's long borders against multiple attacks from many directions. The dubious loyalty of some military personnel did not help matters. Yugoslav fighter aircraft and anti-aircraft artillery brought down about 90–100 enemy aircraft, but defending forces were unable to make any significant impact on the enemy advance. During the attack of German aircraft on Niš Airport Medoševac on 6 April around 08:00, fire from the ground shot down the plane of German fighter ace Herbert Ihlefeld. Captain Ihlefeld, who was credited with over forty air victories, was shot down by Corporal Vlasta Belić, firing a Darne machine gun, caliber 7.7 mm, taken from a Yugoslav Breguet 19. Having received a shot in the oil cooler, the Bf 109's engine stopped, and the pilot was forced to leave the plane. He rescued himself with a parachute about 35 miles southeast of Nis. The German ace was captured by Serbian peasants who handed him over to the gendarmes. On April 17, 1941, the Yugoslav government surrendered. Several VVKJ aircraft escaped to Egypt via the Kingdom of Greece, and the crews then served with the British Royal Air Force (RAF).