Meanwhile, Kaptlt Hans-Joachim Schmidt-Weichert’s U9 was nearing operational readiness, departure for her first patrol delayed until Petersen’s return to allow evaluation of his experience with the enemy and torpedo failures. U9 had sailed against Britain and France during 1940 under the command of Wolfgang Lüth, destined to become one of the most highly decorated U-boat captains of the war. The boat sported a large Iron Cross on either side of the conning tower – created by Lüth’s crew in remembrance of Otto Weddigen’s U9 from the last war, Weddigen Germany’s first U-boat ace. Schmidt-Weichert took the Iron-Cross boat from harbour at 7 a.m. on 11 November, bound for the same operational area that U24 had occupied. The patrol was relatively uneventful with only weak Soviet naval units found at sea and avoided by diving. A single steamer estimated at 1,500 tons was missed by torpedo shot and ultimately, the twenty-one-day patrol achieved nothing except the successful photographing of Poti harbour – U9 returning after fuel ran low.
Finding minimal Soviet targets, the U-boats were ordered to extend their patrol area north to Pitsunda Point, opening the hunt for merchant shipping. U24 put to sea once more on 24 November, her new skipper ObltzS Clemens Schöler. Five days from harbour, at 12.15 p.m., Schöler’s boat was shelled by three salvoes of Turkish coastal artillery while sailing eastwards seven nautical miles offshore, forcing the boat underwater to safety. By the beginning of December, intelligence reports indicated the return of large units of the Soviet fleet to Poti and Batum and Schöler immediately headed for the harbour approaches to lay in wait. He had already attempted to torpedo a Soviet destroyer but missed as the ship zigzagged. However, the Soviet fleet movements were completed by 5 December and Schöler prowled further north. Strong phosphorescence in the water was proving problematic for the U-boat at night, the shiny wake betraying the small craft’s presence. It was another barren patrol, U24 returning to Constanta after twenty-two days at sea and one unsuccessful Soviet air attack:
The Führer’s order for more supplies to be sent to Army Group A via the Crimea and the halting of shipping to Nikolaiev have created a new situation. As a result the main convoy traffic has now been switched from Constanta and the Danube to Sevastopol and Kerch.The available escort forces will be fully occupied. Russian submarines operating close inshore prove the greatest menace to convoys. Convoys proceeding to the Crimea must therefore avoid the coast and constantly vary their route … In view of the present general situation and of Russian opportunities for interfering with our supplies, U-boat operations against warships continue to be the main task. Sinking merchant tonnage off the central east coast can only bring very slight relief to the Caucasus front, I therefore consider that the U-boats should be transferred back to the area off the harbours of Poti and Batum, if only in the hope of to some extent tying down enemy naval activity, [sic] A situation report to this effect has been sent to Group South, U9 has been ordered to proceed at once to the operational area off Poti, to remain there until her return to base, and to attack large merchant vessels and warships from torpedo boat upwards.
U9 sailed once more on 19 December, escorted from harbour by Räumboot R35, but again experiencing frustrating failure. The boat was damaged by eight depth charges from a Soviet minesweeper on 27 December, the starboard deck railing destroyed, stuffing box around the RDF antennae damaged and leaking, deck planking warped and hull slightly dented. Low on fuel – and after failing with a three torpedo shot on a steamer – the boat reached Constanta at 10.39 a.m. on 7 January 1943.
While Schmidt-Weichert had been at sea, the face of the war on Russian soil had irrevocably changed. Axis forces at Stalingrad had collapsed; the final organised resistance ending on 2 February when Generaloberst Karl Strecker surrendered to Soviet forces. A pivotal moment in the war on the Eastern Front, Germany suffered some 400,000 casualties, but the battle was also a significant disaster for Romanian, Hungarian and Italian troops. Even a Croatian unit was lost in the maelstrom, news of which was withheld from the German public until the end of January.
Schöler took U24 to sea once more on 18 January, followed three days later by newly available U19, skippered by Kaptlt Hans-Ludwig Gaude who had just completed three weeks of training for his crew in the waters around Constanta. Gaude was ordered to the area between Sochi and Tuapse, refuelling on both outward and inbound journeys at Feodosia in order to extend the patrol length. Instructions included the code word Panthersprung, which would direct U19 to occupy a reconnaissance line south of Kerch and west of Novorossiyk, joining U24. During the previous November the Soviet ground offensive that had isolated Stalingrad had also battered its way to the shores of the Sea of Asov; the German 1st Panzer Army pushed back to Rostov and 17th Army towards the Taman Peninsular into what became the Kuban Bridgehead (known as Gotenkopf – Gothic Head – to the Wehrmacht). By February 1943 German troops had fallen back from Krasnodar to the Kuban defensive positions. For once, Hitler had authorised the strategic withdrawal not only to protect the eastern approaches to the Crimea but also to provide a launching point for future offensives against the Caucasus during 1943. Meanwhile Luftwaffe reconnaissance noted a build up in Soviet forces within ports along the Black Sea and OKW foresaw a major Soviet seaborne landing against the Kuban bridgehead.
On 4 February the Russians struck: landing troops at Cape Myskhako near Novorossiysk. Weak Kriegsmarine opposition allowed the successful ferrying of 150,000 men, 4,600 horses, 387 tanks, 463 guns, 106 rocket launchers, 3,000 tons of ammunition, 52,000 tons of supplies and 15,000 tons of oil and gasoline into action against the German lines during the first three months of 1943. If German attention had weighed more heavily on obliterating Soviet naval stations on the Caucasian coast, it is conceivable that the Wehrmacht’s war on land may have been eased: the Soviet coastal convoys and escorts denied their bases. As it was, Soviet troops concentrated on the recapture of Novorossiysk or, at least, the deprivation of the harbour to the Germans.
The attack had begun at midnight with Russian naval units shelling German shore batteries near Anapa and air raids within the German lines. At 1.05 a.m. the code word Panthersprung was issued and both U19 and U24 began to move toward their patrol line:
Report received from Naval Shore Commander, Caucasus that the enemy landed two tank battalions near Osiereika and south of Novorossiysk; single craft landed more troops near Sudchikaya, Countermeasures in progress. Attempts of weak forces to land in Novorossiysk harbour driven off. Further landing attempts, bringing up of reinforcements to earlier landing sites and support of Russian land operations by gunfire from cruisers and destroyers at sea must be expected in the coming night. The patrol lines (Panthersprung) assigned to U24 and U19 are too far north to be an effective defence. I have therefore decided to station the boats as close to the coastal landing site as possible and they have been ordered to take up a patrol line from air grid square 3539 (lower edge centre) to air grid square 7547 (lower right-hand corner).
The main attack at Novorossiysk was wiped out, but another beachhead at nearby Mount Myshako held out and was reinforced to 17,000 men within days. Soviet entrenchment closed the harbour to German use and, despite fierce land attacks, the Russian lines held.
U9, having departed Constanta bound for refuelling in Feodosia, was also ordered to join the Panthersprung boats on 6 February while U24 was forced to leave for refuelling. Schöler had already missed two ships with torpedoes: one 500-ton netlayer and a 1,500-ton steamer untouched, despite U24 having shadowed the steamer for a full day before attacking. He had also sighted a formation of two cruisers and destroyer escorts but was too distant to intervene.
On 11 February U19 also refuelled in Feodosia, taking fuel, water and provisions from the moored tanker Breslau as well as repairing a damaged compressor. Gaude reported an unsuccessful attack on two Soviet destroyers at the beginning of February, but nothing else sighted. Vizeadmiral Witthoeft-Emden (Admiral Black Sea) was frustrated by the U-boats’ lack of enemy contact, reasoning that enemy supply convoys were hugging the coastline. Nonetheless, he maintained that they must be intercepted in order to relieve some of the pressure on German lines ashore. Correspondingly the Panthersprung boats were ordered to fresh patrol zones: U9 to the coast between Ghelenjik and Tuapse; U24 between Adler and Cape Pitsunda; and U19, after refuelling in Feodosia, to the former patrol line south of Novorossiysk. All three boats achieved nothing. U19 missed a destroyer with another spread of three torpedoes on 15 February before the boat began her return to Constanta. Likewise U24 reported pistol failures on two torpedoes fired at Soviet destroyers and a lack of merchant targets despite Luftwaffe reports of heavy shipping within his patrol area.
The last of the trio, U9, had taken the chance at Feodosia to have welding done on the conning tower before joining the Panthersprung. The boat was shelled from land and attacked by aircraft during the patrol, the periscope strafed by Soviet fighters but undamaged. Despite a malfunctioning echo-sounder and gyro-compass, the boat was refuelled and reprovisioned again in Feodosia on 26 February and sent to the sea off Anapa to search for Soviet destroyers shelling German positions ashore. The hunt yielded nothing and U9 reached Constanta on 3 March, the final leg of the journey escorted by a BV138 flying boat of Seeaufklärungs-Fliegergruppe 125.
Both U19 and U24 were at sea during the latter half of March. Gaude’s U19 prowled the sea-lanes off Sevastopol and Kerch, destroying floating mines with sub-machine-gun fire and attacking an unidentified passenger steamer on 23 March with a full bow salvo of three torpedoes. Strong detonations were heard within the submerged U-boat and Gaude observed what he recorded as a 2,500-ton ship lying stopped through his periscope. Escorting minesweepers dropped four depth charges but failed to damage the retreating boat. Nevertheless, mechanical problems with the starboard drive shaft forced a return to Constanta, Rosenbaum recording the patrol as ‘clear and considered’ after debriefing the young skipper.
Schöler’s U24 had actually encountered Gaude’s boat while at sea on 22 March, making an emergency dive to safety as he believed U19 to be Russian. Dodging aircraft over the days that followed, U24 finally sighted a worthwhile target on the last day of the month. At 12.15 p.m. a tanker escorted by two destroyers and a minesweeper were sighted near the coast at Pitsunda in Gagri Bay. Fifteen minutes later Schöler launched two torpedoes and claimed a hit on 8,228-ton Sovetskaja Neft as the tanker began to burn. Soviet sources report that ship already damaged by Luftwaffe torpedoes on 26 March in Tuapse and it seems likely that Schöler had actually attacked the 7,661-ton tanker Kreml’ which remained afloat despite the damage and ensuing fires aboard. The Soviets had begun to fill only the central shore-side compartments of their tankers for such voyages, the vulnerable bow, stern and seaward compartments used instead for ballast lest they be attacked by Luftwaffe, S-boat or U-boat torpedoes. With the tanker ablaze escorting minesweepers, supported by a pair of MBR-2 aircraft, began dropping depth charges around the submerged U-boat that caused some minor damage. Amidst the cacophony of explosions, Schöler recorded the sound of sinking noises heard through the water and erroneously claimed the misidentified tanker as sunk. U24 was eventually able to shake loose her pursuit and headed for Feodosia for resupply with fuel and provisions and conduct minor repairs before returning to sea at 12.30 p.m. on 10 April. Schöler was to participate in Operation Neptune – the clearing of the Soviet bridgehead at Novorossiysk:
If they follow their previous custom, the enemy will probably bring up reinforcements to the beachhead from Kabardinka Bay, Ghelenj’ik and Tuapse. Any evacuation will probably be carried out by the same route. As the Army operations are receiving strong support from the Luftwaffe, I presume that the enemy will not be able to bring up supplies or carry out evacuation by sea during the day. They will thus be compelled to bring up their naval transports at night. My duty is to prevent this. All my offensive forces will be sent into the area between the beachhead and Tuapse concentrating on the stretch between Myshako and Cape Doob.
On 31 March, Soviet troops had defeated the German 17th Army in the Kuban Peninsula and captured Anastasyevsk north of Novorossiysk. A fresh Soviet offensive was launched in early April, attempting to push the Germans out of the Taman Peninsula while the Wehrmacht’s 17th Army in turn attempted to destroy the Soviet bridgehead around Novorossiysk.
German reinforcement of Anapa was intended to allow the final destruction of the enemy bridgehead at Mount Myshako; the U-boats – and S-boats of the 1st S-flotilla – assigned interception of coastal supply traffic to Mishako. Schöler was ordered upon receipt of the code word Jagdkönig to operate as long-range escort for one of the frequent army convoys resupplying troops at Anapa and the Wehrmacht’s tenuous grip on the Taman Peninsular. While wounded men and civilians were convoyed west to the Crimean Peninsula, whatever combat units could be flung into the line, along with ammunition and supplies, were transported east in what would ultimately prove a vain defence.
Once in the operational area U24 was to patrol during daylight between Cape Idokopas and Tuapse: from dusk until dawn between Chugovkopas and Tuapse as close to the coast as possible, with torpedo attacks made on any and every worthwhile target. Once the operation was over, U24 would be given fresh radioed instructions.
Schöler sailed as planned on 10 April while in Constanta U19 was being readied for sea once more, but after two days at sea Schöler reported recurring mechanical problems with U24’s port engine, forcing a return to Constanta. This interfered with Neptune’s plans and so Gaude’s U19 was ordered to replace U24. Neptune had already been postponed several days in a row due to low-lying cloud cover preventing Luftwaffe support, the army’s vacillation rendering S-boat participation hazardous in the extreme due to the moon state making them particularly vulnerable to ground fire.
Gaude sailed on 14 April toward Tuapse alongside U9 as part of Neptune, the operation finally beginning at 6 a.m. on 17 April. While S-boats were heavily engaged in the attack, U19 experienced a frustrating lack of targets. Gaude was cleared to attack any shallow-draught troop-carrying lighters with torpedoes following an attempted Soviet submarine attack on a German barge carrying the wounded away from the front line. Still no opportunities arose. Finally, on 24 April, Army Group A suspended Neptune after gaining little headway and suffering heavy casualties. U19 was released to head to the area between Cape Uchdere and Gagri, still finding nothing. On 27 April, Gaude reported Matrosen Kirstein sick with a high fever, rendezvousing with S-boat S51 the following day and transferring the ill man aboard for high speed transfer to hospital. Three failed torpedo shots against an enemy destroyer on 29 April marked the sole encounter with the enemy and U19 returned after twenty-one days at sea.
Schmidt-Weichert’s U9 had also achieved little during its twenty-four days at sea. After parting company with the returning U24, U9 had attacked the damaged tanker Kreml’ at 2.41 p.m. on 5 May, one of three torpedoes fired at the escorted ship detonating after ten minutes and mistakenly taken as a hit. Six depth charges followed, buffeting the U-boat, which escaped unharmed. U9 was back in Constanta on 10 May.
The first of the three reinforcements arrived for Rosenbaum’s flotilla during early May: U18 recommissioned into the Kriegsmarine on 6 May; followed later by U20 on 26 May and U23 on 3 June. Despite their transit from Germany delayed by ice, all three boats were operational by June. Rosenbaum reshuffled his crews; ObltzS Clemens Schöler transferred to take command of U20, his place in U24 retaken by ObltzS Klaus Petersen, while U23 was skippered by ObltzS Rolf-Birger Wahlen, former watch officer aboard an Atlantic U-boat.
Meanwhile U9 sailed once more from Constanta on 20 May, escorted by two R-boats and a Heinkel He 114 float plane. The patrol took a familiar path; the occasional floating mine destroyed by machine-gun or sub-machine-gun fire: diving to escape Soviet air attack after a brief flurry of shots from the boat’s flak weapon. On 26 May the boat was shelled by Soviet artillery south of Novorossiysk, escaping by submerging. Two days later Soviet MTB TK106 encountered the boat and dropped eight depth charges that caused light damage but did not impede the patrol. The boat was again depth charged at the beginning of June and machine gunned by strafing aircraft that narrowly missed inflicting injury. After meeting and exchanging information with ObltzS Karl Fliege’s U18, Schmidt-Weichert headed for Feodosia to resupply from the tanker Inga, taking on board fuel and provisions. On 12 June, the boat docked in Constanta with no success claimed, transferred to the shipyard in Galati where U9 received a complete overhaul and the damaged conning tower repaired. She would not sail again until August.
Schöler’s first patrol with U20 was cut short after only eight days; a heavy air attack on the evening of 25 June forcing the boat under but with no real damage. During the days that followed Schöler attempted to torpedo an ASW trawler and received eight depth charges for his trouble, followed by hours of air attack during which twenty-one depth charges were dropped around the boat. With the bilge pump non-operational, U20 returned to Constanta on 29 June.