On 4 June 1943 the operation began. Although the night was moonlit, KG 55 utilised the Radio Moscow frequencies as a navigational aid. Soviet retaliation occurred in the form of counter-air raids against its airfield on 8 and 18 June. II "Gruppe" took part in the bombing operation against rail lines at Kursk on 2 June. From 4 June it participated in the attacks on the tank factory at Gorki, the refineries and ball bearings at Saratov as well as Yaroslavl. The 4/5 June operation was carried out by 128 He 111s and Junkers Ju 88 from III./KG 1, KG 3, II and III./KG 4, KG 27, I./KG 100 and II. and III./KG 55 dropped 179 tons of bombs against the No. 1 Molotov plant. Many workshops of wooden construction caught fire. The water-supply was severed and large parts of the plant burned. The blacksmiths, chassis, main conveyor, and spring workshops were destroyed. Living compounds and a child's nursery were also hit. The effect was disastrous for the Soviets. The attackers lost five bombers. The Soviet 1st Air Army, 2nd Air Army and 15th Air Army attacked German airfields on 8 June. JG 51 intercepted, and claimed 40 for one loss.