'Iskra' was a Soviet offensive, otherwise known as the '4th Sinyavino Offensive Operation', to reopen a land corridor into Leningrad (12/30 January 1943).
The city had been cut off since 15 September 1941, when Generaloberst Georg von Küchler’s (from 16 January 1942 Generaloberst Georg Lindemann’s) 18th Army, the northernmost formation of Generalfeldmarschall Wilhelm Ritter von Leeb’s (from 17 January 1942 von Küchler’s) Heeresgruppe 'Nord', took Petrokrepost (Schlüsselburg in German) on the southern side of Lake Ladoga.
In Leningrad the second winter of the siege was not as bad as the first. While Lake Ladoga was open, boats had been able to deliver supplies for the troops and civilians, and to evacuate almost 500,000 persons. A German attempt to use Siebel catamaran ferries, driven by aircraft engines and mounting a light anti-aircraft gun, to interdict the Soviet traffic across the lake had failed. In the autumn of 1942 the Soviets had laid an electric cable and a petrol pipeline in the lake, and after the lake had frozen they built an ice road and set up high-tension electricity lines. In Leningrad, therefore, the people had enough food at least to survive and there was sufficient electricity to operate at least some of the city’s industrial facilities. What was undeniable, though was that the 5,000 or 6,000 tons of supplies which trucks could deliver across the ice each day could barely sustain both the city and the front. Normally the second largest industrial centre in the USSR, Leningrad was capable of a far greater contribution to the Soviet war effort than it was now making through the operation of facilities within sight of the front for propaganda as much as for production.
So, after the failure of their first attempt to overcome the siege in the '3rd Sinyavino Offensive Operation' between August to October 1942, General Polkovnik (from 17 November General) Leonid A. Govorov’s Leningrad Front and General Kirill A. Meretskov’s Volkhov Front had swiftly been instructed to begin the build-up for another relief offensive. As the long dark of the winter months arrived, reinforcements from the east crossed Lake Ladoga and moved into the Leningrad Front’s line.
Heeresgruppe 'Nord' watched these Soviet development with some anxiety. Occupying a relatively inactive front, this army group had been neglected throughout most of 1942, had not be able to complete any full replacement of the losses it had suffered during the previous winter, and was tied into a static defence which could be assaulted at any of several critical points. Around Leningrad, and most especially at the 'bottleneck' (Flaschenhals), the army group’s salient to the southern shore of Lake Ladoga between the eastern bank of the Neva river in the west and the area between Lipka and Bugry in the east, Heeresgruppe 'Nord' functioned as the main support of German strategy in northern Europe, but if the German hold on Leningrad were to be broken, Germany would inevitably start to lose control of the Baltic Sea: Finland would then be isolated; the flow of Swedish iron ore by ship would be endangered; and the all-important U-boat training areas in this sea would be seriously threatened.
In the 16 months it had held the Flaschenhals, Heeresgruppe 'Nord' had created a dense network of defences in the swampy terrain and had converted Schlüsselburg, several smaller settlements, and scattered patches of woods into fortified strongpoints. But, with only 6 to 9 miles (10 to 14.5 km) between the two fronts of the 'bottleneck', one facing west and the other east, the defenders had almost no room for manoeuvre. The Soviets had learned many important tactical lessons during the fighting for this area during the summer and autumn of 1942, and in the following three months had rehearsed every possible tactic and manoeuvre for taking each of the individual German positions. This was the method which the Germans themselves had used in 1940 to train for the assaults on the Belgian forts in 'Sichelschnitt'.
Thus, in the period following the failure of the '3rd Sinyavino Offensive Operation' within the context of their great winter offensive of 1942/43 along the full length of the Eastern Front, the Soviets had carefully planned and rehearsed an altogether more professional undertaking using larger forces on a smaller front to ensure overwhelming superiority of strength.
General Major Mikhail P. Dukhanov’s 67th Army of Govorov’s Leningrad Front had trained with great intensity throughout the second half of December 1942 for the extremely difficult task of launching itself across the ice of the Neva river straight into the Germans' fixed defences. On 25 December, a meeting of commanders, including Marshal Sovetskogo Soyuza Kliment Ye. Voroshilov as the Stavka supervisor of the operation, looked into questions raised by the programme of exercises preceding the operation proper, and until a time well into the first week of January 1943 regiments underwent special training on the Toksovsky grounds to learn how to move through 'fire walls' created by the Soviet artillery. The 67th Army had no combat experience on which to draw for lessons in the assault of heavily fortified positions, and it was for this reason that the period of intensive training was essential.
From the west the 67th Army was to advance to the east across the Neva river between Lake Ladoga and Nevskaya Dubrovka, and from the east General Leytenant Vladimir Z. Romanovsky’s 2nd Shock Army of Meretskov’s Volkhov Front was to push to the west between Lake Ladoga and Gontovaya Lipka, it being planned that the two formations meet to the north of Sinyavino and thus create a narrow land corridor into Leningrad from the east. The 2nd Shock Army’s left flank was supported by General Leytenant Filipp N. Starikov’s 8th Army.
'Iskra' thus pitted 20 Soviet divisions and 15 brigades supported by 4,600 pieces of artillery, 500 armoured vehicles and 900 aircraft, against six Germans divisions supported by 700 pieces of artillery, 50 armoured vehicles and an unknown number of aircraft.
The main German formation threatened by 'Iskra' was General Ernst von Leyser’s XXVI Corps, supported to the south by General Erik Hansen’s LIV Corps.
The area to the south of Lake Ladoga in which 'Iskra' was to be fought was heavily forested, with a considerable area of wetland (notably peat deposits) closer to the lake, and the density of this forested area shielded each side from visual observation. These were factors which each played a significant part in reducing the mobility of vehicles and artillery, which was of greater importance to the German defence than the Soviet offence. So far as terrain factors were concerned, a key feature was the Sinyavino heights, some 490 ft (150 m) higher than the surrounding flat terrain: these constituted one of the few dry and clear areas, and in addition provided good fields of observation.
Since the front line had changed very little since the start of their siege of Leningrad, as noted above, the German forces had built a dense network of defensive strongpoints, interconnected by trenches and protected by extensive obstacles, minefields and interlocking zones of artillery and mortar fire. The Germans also appreciated that the Neva river and its associated marshes were partially frozen in winter to a depth that allowed the passage of infantry but not of heavy vehicles.
The Germans were only too well aware that the breaking of the siege was a matter of great importance to the Soviets. However, the imminent defeat of Generalfeldmarschall Friedrich Paulus’s 6th Army in Stalingrad and the Soviet 'Velikiye Luki Offensive Operation' to the south of Leningrad combined to result in orders for Heeresgruppe 'Nord' to go on the defensive and provide many formations for diversion to areas deemed to be under greater threat: for example, much of Generalfeldmarschall Erich von Manstein’s 11th Army, which was to have led the assault on Leningrad in September 1942, and which had thwarted the last Soviet offensive, was transferred to Heeresgruppe 'Mitte' in October, and nine more divisions were also reassigned to other sectors.
At the start of 'Iskra', therefore, the 18th Army comprised 26 divisions spread across a front 280 miles (450 km) long, and as a result the army’s formations were stretched very thinly and possessed no division-sized reserves. Rather each division had a tactical reserve of one or two battalions, and the army reserves consisted of portions of Generalleutnant Ferdinand Nöldechen’s 96th Division and Generalleutnant Dr Julius Ringel’s 5th Gebirgsdivision. Air support for Heeresgruppe 'Nord' in general, and the 18th Army in particular, was the responsibility of Generaloberst Alfred Keller’s Luftflotte I.
Five German divisions and part of a sixth held the narrow corridor which separated the Leningrad Front and the Volkhov Front. In this Flaschenhals area, the German divisions were well fortified as the front line had remained almost unchanged since September 1941.
The Soviet plan for 'Iskra' was approved in December, and called for the Leningrad Front and Volkhov Front to defeat the Germans in the area bounded in the east by Lipka and Gontovaya Lipka, in the west by Schlüsselburg and Nevskaya Dubrovka, in the north by Lake Ladoga, and in the south by Sinyavino, thereby breaking the siege of Leningrad by end of January 1943. This meant the seizure of the 'bottleneck' and the opening of a corridor some 6 miles (10 km) wide, to Leningrad. After that, the two fronts were to rest for 10 days and resume their offensive to points farther to the south in order to widen the east.west corridor created in 'Iskra'.
The primary difference between the '3rd Sinyavino Offensive Operation' and 'Iskra' lay in the location at which the latter’s main attack was to be delivered. In September 1942 the Soviet forces had attacked in the area to the south of Sinyavino, just to the north of Tosno, which gave them the possibility of encircling several German divisions, but also left them vulnerable to flanking attacks from the north, which was in fact what caused the offensive’s failure. 'Iskra' was now to be undertaken in the area to the north of Sinyavino, and thus closer to the southern shore of Lake Ladoga, which on the one hand removed the threat of flanking attacks and thereby increased the chances of success, but on the other hand forced the Soviets to abandon the idea of encircling most of the German forces in the 'bottleneck' and thereby reduced the scale of any victory.
In 'Iskra', the main weight of the offensive’s converging thrusts was to be delivered by Dukhanov’s 67th Army from the west and Romanovsky’s 2nd Shock Army from the east, while Starikov’s 8th Army was to undertake a limited offensive on the 2nd Shock Army’s left flank and defend elsewhere. Air support was to be provided by General Leytenant Stepan D. Rybalchenko’s 13th Air Army and General Leytenant Ivan P. Zhuravlev’s 14th Air Army.
The formations of the two fronts allocated to 'Iskra' also received major strengthening in the form not only of replacements and additional divisions and brigades, but also of additional artillery and engineer units deemed essential for the difficult task of breaching the Germans' prepared defences. Specialised winter warfare units included three ski brigades and four aerosled battalions.
Moreover, to ensure that the Soviet forces would operate under an umbrella of air superiority, which they had lacked in the '3rd Sinyavino Offensive Operation', the air strength in the area was increased to more than 800 aircraft, most of them fighters.
The swampy terrain over which much of 'Iskra' was to be fought was unsuitable for the deployment of major tank forces, so the armoured support comprised mostly tank battalions reinforcing divisions or the enlarged brigades that were to operate independently.
The start of 'Iskra' was initially scheduled for 1 January, but the poor condition of the ice on the Neva, which the 67th Army would have to cross, led to a delay to 10/12 January. To reduce the chance of any of the operation’s details falling into German hands, only a small number of senior officers were involved in the planning, all redeployments took place in bad weather or at night, and attack preparations were simulated in other areas to confuse the Germans. On 10 January the Stavka despatched General Georgi K. Zhukov as its representative to co-ordinate the battle, on the following day the Soviet divisions and brigades occupied their jumping-off positions, and on the day after this the first-echelon tank units moved into their advanced positions early.
During the night of 11/12 January Soviet bombers attacked German divisional headquarters and artillery positions to disrupt the German command and control capability, and also attacked German airfields and communication centres to disrupt the flow of reinforcements.
'Iskra' proper started at 09.30 on 12 January as the two Soviet fronts began their artillery preparation, which employed 286 pieces of artillery and lasted for 140 minutes on the western side and 105 minutes on the eastern side, and the attack started five minutes before the artillery preparation finished with an area-saturating barrage of Katyusha unguided artillery rockets. The forces of the Leningrad Front achieved their greatest success between Schlüsselburg in the north and Gorodok 1 in the south. Here the 136th and 268th Divisions, with supporting tanks and artillery, seized a bridgehead across the Neva river some 3.1 miles (5 km) wide and 1.9 miles (3 km) deep. At 18.00 the Soviet engineers constructed bridges near Mar’ino to allow second-echelon troops to advance. Attacks farther to the south, near Gorodok 1, resulted in the capture of only the first line of German trenches, however. In the extreme north the attack on Schlüsselburg failed. By the fall of night, the Leningrad Front had decided to exploit the bridgehead its men had gained, and the troops attacking Schlüsselburg across the Neva were redeployed into the bridgehead and started an attack from the south in the direction of Schlüsselburg.
The Volkhov Front’s attack was less successful, the 2nd Shock Army managing to envelop but not to destroy the German strongpoints at Lipka and Workers' Settlement No. 8. The latter was an impressive position with 16 bunkers and held by 700 men. Heavy flanking fire from these strongpoints prevented further Soviet advance, but the 2nd Shock Army penetrated the German defences to a depth of some 1.25 miles (2 km) between these points. Still farther to the south, between Workers' Settlement No. 8 and the Kruglaya wood, the advance was 0.6 to 1.25 miles (1 to 2 km) deep, but still farther to the south the 8th Army’s flanking effort managed to capture only the first line of German trenches.
The Germans immediately started to move reserves to the region. One Kampfgruppe, comprising of five battalions of the 96th Division, supported by artillery and four PzKpfw VI Tiger I heavy tanks, moved to Gorodok 2 to reinforce Generalleutnant Erwin Sander’s 170th Division to the west. A similar Kampfgruppe, again based on battalions of the 96th Division, was sent to Workers' Settlement No. 1 to support Generalleutnant Friedrich von Scotti’s 227th Division.
During the five days which followed, there was very heavy fighting as the Soviets advanced slowly through the German defences and repelled German counterattacks. On January 13 adverse weather prevented the Soviets from using their air power, and on that day the Soviets gained almost no ground and suffered heavy losses. After their counterattacks had failed to throw back the Soviet troops, the Germans started a further reinforcement of the area by assembling Kampfgruppen drawn from divisions deployed on quieter parts of the front. These included Kampfgruppen from Generalleutnant Martin Grase’s 1st Division, Generalleutnant Werner Hühner’s 61st Division, Ringel’s 5th Gebirgsdivision and Generalleutnant der Polizei Alfred Wünnenberg’s SS Division 'Polizei'.
On January 14 an improvement in the weather allowed flying once more and the Soviet advance resumed, albeit at a slow pace. To accelerate the encirclement of the strongpoint at Lipka, to the east of Schlüsselburg on the southern shore of Lake Ladoga, the Soviets used the 12th Ski Brigade, which crossed the lake’s ice and attacked the German garrison’s lines of communication. By the end of the day the German forces in the areas of Lipka and Schlüsselburg had been almost entirely cut off.
In the period between 15 and 17 January the forces of the Soviet fronts fought their way toward each other, capturing the strongpoints at Workers' Settlements Nos 3, 4, 7 and 8, and most of Schlüsselburg. By the fall of night on 17 January the Soviet western and eastern spearheads were only 0.9 to 1.25 miles (1.5 to 2 km) apart between Workers' Settlements Nos 1 and 5.
At 09.30 on 18 January the leading units of the 67th Army’s 123rd Division and the 2nd Shock Army’s 372nd Division met near Workers' Settlement No. 1, thus technically breaking the blockade and marking an important date in the siege of Leningrad and, in the process, cutting off the German forces north of the settlement. The Gruppe 'Hühner', led by Hühner, commander of the 61st Division, and comprising a pair of Kampfgruppen, was supposed to hold open the corridor between Workers' Settlements Nos 1 and 5, but was unable to do so. Later on the same day the Soviet forces captured Workers' Settlement No. 5 after repelling a strong German counterattack. The leading units of the 67th Army’s 136th Division and the 2nd Shock Army’s 18th Division linked to the north of the settlement at 11.45. The Gruppe 'Hühner' was also cut off, and ordered to break out through the forested area toward Sinyavino before the main Soviet forces arrived and made such an escape impossible. After abandoning its artillery and heavy equipment, the Gruppe 'Hühner' ran a gauntlet of Soviet fire in the 'corridor of death' to reach Sinyavino on 19/20 January. This break-out was costly for each side.
By a time early in the afternoon, the Soviet forces had cleared Schlüsselburg and Lipka, and started the destruction of the forces remaining in the forests lying to the south of Lake Ladoga. During 19/21 January the Soviet forces steadily completed the destruction of encircled German forces and tried to expand their offensive to the south in the direction of Sinyavino. Here the 18th Army had significantly reinforced its positions with the SS-Polizeidivision, Generalleutnant Otto Sponheimer’s 21st Division, and soon after them Generalleutnant Siegfried Thomaschki’s 11th Division and Generalleutnant Johann Sinnhuber’s 28th Jägerdivision.
The Soviet forces captured Workers' Settlement No. 6 but were unable to advance any further. There were no changes in the front after January 21. Unable to advance farther, the Soviet forces then started to fortify the area they had taken as the primary means of preventing any German attempt at re-establishing the siege of Leningrad.
On 22 January work began on the re-establishment of the railway link between Leningrad and the rest of the USSR through the captured corridor, and traffic started to move along the new track on 6 February, one week after the end of 'Iskra', which had cost the Soviets 33,940 men killed and missing together with 81,140 wounded and sick, and the Germans 12,000 killed and an unknown number wounded.
In overall terms, 'Iskra' had been a small but major strategic victory for the Soviets. The operation had removed all possibility of the capture of Leningrad and a junction between the Germans and the co-belligerent Finns, and also opened the way to the revitalisation of the Leningrad Front with men, ammunition and supplies for a more effective co-operation with the Volkhov Front. For Leningrad’s civilians, 'Iskra' meant that more food could reach them and more of them could be evacuated from the city.
The breaking of the German siege also had a major strategic ramifications, although this was overshadowed by the surrender of the last German pocket in Stalingrad on 2 February. As well as a promotion for Govorov, the success of 'Iskra' meant the elevation of Zhukov to the rank of Marshal Sovetskogo Soyuza on 18 January.
On the other side of the revised front, the 18th Army had been much depleted, and its surviving formations were exhausted. Lacking sufficient reinforcements, Heeresgruppe 'Nord' decided to shorten its front line by evacuating the Demyansk 'pocket' (in fact salient) during March. The pocket been held throughout 1942, despite being encircled for a few months, as it was an important strategic bridgehead. Together with the Rzhev salient, which was also evacuated in the spring of 1943, it could have been used as a springboard for the encirclement of considerable Soviet forces.
Despite its success, the Stavka appreciated the fact that 'Iskra' was an incomplete victory, for the new corridor into Leningrad was narrow and still lay within German artillery range. Despite the intensity of the German bombing and mining, the Ladoga 'ice road', augmented by a fuel pipeline, thus continued to carry essential supplies, but with the new railway a greater volume of coal as well as food and other essentials could be delivered. The starvation which had killed so many in Leningrad was now slightly less severe, but the attempt to widen the land route to Leningrad, by taking Mga and thereby opening the railway line linking Leningrad and Volkhov, failed as German reserves poured into the area of Sinyavino, where the important heights and strongpoint were still in German hands. This led Zhukov to plan a considerably more ambitious offensive as 'Polyarnaya Zvezda' to inflict a strategic defeat on Heeresgruppe 'Nord'. This undertaking faltered at an early stage, however.
The Soviets undertook several other offensives in the area during 1943, slowly expanding the corridor and making other small gains before finally capturing Sinyavino in September. However, Leningrad was still subjected to at least a partial siege as well as air and artillery bombardment until January 1944, when the 'Leningrad-Novgorod Offensive Operation' finally broke clear through the German lines and ended the siege.