While the bulk of the Luftwaffe was busy with the land battle, III./KG 26 sought to break Soviet sea communications. They sank the tanker "Mikhail Gromov", but the flotilla leader "Tashkent", the destroyer "Bezuprechnyy", and transport "Abkhaziya" escaped to bring 2,785 soldiers into the fortress. Air support continued with 643 sorties on 3 June, 585 on 4 June, and 555 on 5 June, with some German crews flying daily averages of 18 missions. By the start of the ground attack on 7 June, the Luftwaffe had flown 3,069 sorties and 2,264 tons of high explosive and 23,800 incendiary bombs were dropped. Many of the bombs dropped were 1,000 kg SC 1000, 1,400 kg SC 1400, and 2,500 kg SC 2500 bombs. The heavy-caliber weapons were aimed at Soviet concrete bunkers. Ivan Laskin, commanding the 172nd Rifle Division in the northern sector recalled, "Bombers in groups of twenty to thirty attacked us without caring for their targets. They came in, wave after wave, and literally ploughed up the earth throughout our defence area. German aircraft were in the air above our positions all day long. The sky was clouded by smoke from explosions of thousands of bombs and shells. An enormous dark grey cloud of smoke and dust rose higher and higher and finally eclipsed the sun". The German air campaign against Sevastopol in June 1942 surpassed by far the German bombings of Warsaw, Rotterdam or London. From 3 to 6 June, the Luftwaffe carried out 2,355 operations and dropped 1,800 tons of high explosives.