Germans Begin Assault on Secondary Defense Line at Sevastopol
After expelling the Soviets from the Crimea, the German attention turned once again to Sevastopol.
To help with the siege von Manstein had at his disposal some of the largest guns ever built. Along with large numbers of regular artillery pieces, three examples of the six operational super-heavy 600mm Mörser Karl mortars were deployed late in February 1942, and the 800mm "Gustav" railway gun was brought in and deployed for the assault. "Schwerer Gustav" (heavy Gustav) was installed at the former Tatar Khan's palace in Bakhchisaray and required several thousand personnel. It wasn't very useful, but managed once to penetrate 90 feet into an underground ammunition depot.
On 21 May 1942 the Germans launched a bombing and bombardment of the city. On 2 June the main barrage began, and all of the resources of the Luftwaffes Luftflotte 4, commanded by Wolfram von Richthofen, descended on their targets, continuing for five days before the main attack began. On 7 June 1942, the Germans assaulted the secondary defensive line.
Von Manstein's plan for the final assault on Sevastopol, Unternehmen Störfang (English: "Operation 'Sturgeon Catch'"), erroneously postulated that the Severnaia Bay ports constituted a logistic lifeline whose severance would topple the Sevastopol enclave without the Germans having to batter down every inch of it. Since a southward attack from the extreme north sector offered the path of least resistance to the bay, von Manstein decided to commit his main effort there with the 54th Corps, which possessed five divisions beforehand and would receive yet another during the attack. An additional east-to-west holding attack would be delivered by the 30th Corps — comprising three divisions—against the enclave's southern sector to prevent the Soviets from transferring forces across Severnaia Bay to reinforce their northern flank. Each German Corps was supported by a smaller Romanian Corps. This plan disregarded the fact that substantial Soviet supply deliveries to the enclave could not resume, in any event, before autumn returned to fog out the Luftwaffe and that knowing this, the Soviets had hoarded considerable supplies in advance, as they were not able to do before the attacks on the enclave in 1941. Neither Severnaia Bay nor the enclave's entire shoreline constituted the sought-after lifeline. There was no alternative to battering down the entire enclave, were it to be captured.
The outer defensive rings were breached by 16 June 1942, and the 54th Corps soon seized most of the bay's northern shore, yet strong Soviet pockets of resistance held fast on the 54th Corps flanks and even in its rear, while the 30th Corps' westward attack ground to a halt before the Soviet defensive system's bulwark, the so called "Sapun Line", which began almost exactly south of the bay's crown. It became clear that von Manstein's plan had overestimated the effect that incapacitating the Severnaia Bay ports would have on the defenders. On the night of 28 June von Manstein launched an amphibious crossing of the bay aiming to outflank the troublesome Sapun Line. This was an extremely costly operation for which the available German flotilla was hopelessly unsuited, while German aviation and artillery, despite all of their efforts, could do little against the deep subterranean Soviet coastal defences. The Germans attacked ferociously, but the Soviet defenders managed to hang on until nightfall, whereupon they could be reinforced. Despite all of this, von Manstein continued to feed troops into the battle.
Success however, materialized elsewhere. On the Sapun Line's northern end, forces of the 30th Corps—reinforced with the part of the 54th Corps, which von Manstein had decided to land on that tiny stretch of Severnaia's southern shore already captured by the 30th Corps, managed to breach the defences. On the line's southern end, having feigned against the center, German and Romanian troops managed to force through the Soviet defences. Though it was breached at both ends, the Soviets might have tried to hang on to the Sapun Line, but they had run out of shells. The Soviet commander, Petrov, accordingly ordered a withdrawal west to Cape Khersones, where more supplies awaited his men. Cape Khersones was where he intended to make his last stand. The exhausted German forces were unable to immediately pursue and thus allowed the Soviets to reform. Von Manstein launched a massive bombardment of the city of Sevastopol, in order to suppress the defences, though these, with the exception of one stronghold near the shore, were left unmanned because Petrov had naively hoped he could spare the city annihilation.
As the German 11th Army closed in, Stalin himself made it categorically clear that top commanders, Party and administrative officials be brought out by submarine. Oktyabrskii and Petrov were flown out at the last moment. The city fell after the defeat of the Inkerman Heights line on 29 June 1942. The light cruiser Chervona Ukraina ("Red Ukraine"), four destroyers, four cargo ships and the submarines С 32 and Щ 214 were lost. The soldiers fought on even after their installations had been ripped apart by artillery fire. Smoke, which some claim was toxic, forced the troops out into the open, where fire from tanks and the artillery cut them down. Even with this impressive support, the Germans still took twenty-seven days to finish seizing the city proper. On 4 July Chersonesos fell to Germans, and Sevastopol was secured. Hitler, delighted at hearing the good news, phoned von Manstein and commended him as "The Conqueror of Sevastopol", informing him that he had ordered von Manstein's promotion to Generalfeldmarschall. Despite Sevastopol having been taken Soviet troops still held out in the caves around the peninsula until 9 July. The fighting in the officially conquered enclave was, nevertheless, not yet over. There remained a cluster of Soviet pockets that had to be smothered. The ensuing "mopping up" raged on until late autumn, claiming more casualties.
The Germans claimed over 90,000 Red Army soldiers had been taken prisoner, and an even greater number killed. However these claims seems an overstatement, as according to Soviet sources the Soviet garrison defending Sevastopol totaled 106,000 men beforehand, and received only 3,000 in reinforcements during the attack, while it is known that 25,157 persons were evacuated, the overwhelming majority being either wounded soldiers or officers evacuated on Stalin's orders. A more reasonable estimate puts the Soviet losses at 90,000 captured and 11,000 dead.
Soviet accounts claim that there were very few Soviet troops who survived the German onslaught; Von Manstein himself records that the Soviets preferred to blow themselves up along with the German soldiers closing in on their positions rather than surrender. Von Manstein ascribed this behavior to the ruthlessness of the "commissars" and to the basic "contempt for human life of this Asiatic power". Another explanation for the Soviet unwillingness to surrender, was the fear Soviet servicemen had for their treatment if they were taken prisoners of war by the Wehrmacht.
Von Manstein put his own losses at 24,000, a claim that may seem low. However, this figure excludes all Romanian losses, though the Romanians fought well and hard in Sevastopol, rendering an indispensable contribution to the victory. It also excludes all German losses sustained during the "mopping up" fighting after the capture of Cape Khersones. The fall of Sevastopol resulted in Von Manstein's promotion to Generalfeldmarschall, as promised. Hitler and others were deeply impressed by what they perceived as his hardness.
Although a success in the end, the operation had taken much longer than the Germans had imagined. Operation Blau, Army Group South's advance towards Stalingrad and Caucasus was just beginning, and the German offensive would not have the 11th Army to support them.
As has been indicated, the forts of Sevastopol were protected on all sides by dense systems of obstacles: wire, ditches, mines, and others. These obstacles were deranged and to some extent destroyed by the violent bombardments, both from the air and from artillery, which preceded the actual assaults. It was then the mission of the engineers to move forward ahead of the infantry and complete the clearing of paths through the obstacle belts. The detection and removal or neutralizing of mines must have been the most difficult part of the job. For this operation, the German engineers probably depended chiefly on distributed charges of explosives ("Bangalore torpedoes"), which, pushed ahead and detonated, "induced" in turn the detonation of nearby mines. The entire operation demonstrated once again that under present conditions in Europe, a principle function of combat engineers is the removal of obstacles, in the face of enemy resistance.