With the 11th Guards reaching the outskirts of Karachev, midway between Orel and Bryansk, they threatened to cut the main rail line which was the main route of supply. On July 29, Bolkhov was liberated, and on August 4 the struggle for Orel commenced. After one day of hard fighting Orel was taken. With their position untenable, the Germans were forced to evacuate back to prepared positions at the Hagen line. By August 18 Soviet troops had reached the Hagen line east of Bryansk at the base of the Orel salient. With the German defeat the counter-offensive began to grow into a general Soviet offensive. The Voyenno-Vozdushnye Sily (Soviet Air Force) supported the attack on German ground positions in conjunction with the preliminary artillery bombardment. The 1st Air Army and 15th Air Army performed 360 sorties against German rear areas, dropping some of bombs. In the Southern sector of the bulge, the Germans logged over 1,000 missions on the first day, countered by the 737 missions of the 15th Air Army. The Luftwaffe destroyed some 35 tanks, 14 guns and 50 motor vehicles of the Bryansk Front, slowing their progress. By the end of the first day the Soviets had failed to breach the first line. While the 2nd Panzer Army was gradually being forced back, the Luftwaffe battled the VVS, destroying 94 Soviet aircraft on 13 July, including 50 Sturmoviks. In the southern region of the battle the Luftwaffe's "1. Flieger-Division" maintained air superiority in defense of the German 9th Army, dealing the Soviets some significant losses in aircraft between 13 and 16 July. After six days of heavy fighting the strength of the Luftwaffe began to wane. The "1. Flieger-Division" flew 74 intercept missions against the 868 sorties conducted by the 16th Air Army. Though the Soviets continued to lose in tactical air engagements, their overall presence in the air was dominant. The VVS helped the 11th Guards Army achieve their breakthrough. The VVS flew 60,995 sorties and dropped 15,000 tonnes of bombs in support of Kutuzov, while the German "1. Flieger-Division" flew 37,421 sorties and dropped over 20,000 tonnes of bombs on Soviet targets. The battle was the bloodiest of the three major operations during the Battle of Kursk. Overall German losses suffered during the battle were 86,454 men KIA, MIA or WIA.