After the failure of their first assault on Sevastopol, the Axis opted to conduct siege warfare until the middle of 1942, at which point they attacked the encircled Soviet forces by land, sea, and air. On 2 June 1942, the Axis began this operation, codenamed "Störfang" (Sturgeon Catch). The Soviet Red Army and Black Sea Fleet held out for weeks under intense Axis bombardment. The German Air Force (Luftwaffe) played a vital part in the siege, its 8th Air Corps bombing the besieged Soviet forces with impunity, flying 23,751 sorties and dropping 20,528 tons of bombs in June alone. The intensity of the German airstrikes was far beyond previous German bombing offensives against cities such as Warsaw, Rotterdam or London. At the end of the siege, there were only 11 undamaged buildings left in Sevastopol. The Luftwaffe sank or deterred most Soviet attempts to evacuate their troops by sea. The German 11th Army suppressed and destroyed the defenders by firing 46,750 tons of artillery ammunition on them during "Störfang".