'Hannover I' was a German two-phase limited offensive by Generalfeldmarschall Günther von Kluge’s Heeresgruppe 'Mitte' to eliminate the Soviet pocket between Vyaz’ma, Smolensk and Spas-Demensk (24 May/21 June 1942).

The scene was set for 'Hannover I' when, at the end of the winter of 1941/42, the line held by Heeresgruppe 'Mitte' stabilised during April along the leading edges of several Soviet thrusts which had been dangerous during the winter before they were blunted and brought to a halt after penetrating different distance into the German army group’s front. The stabilisation came as the winter ended at a time too early for the Soviets but none too soon for the Germans.

As the two sides took stock of the new situation revealed by the stabilisation of the line, they came to see the many changes which had been effected on the front line: while the straight-line distance between the northern and southern ends of Heeresgruppe 'Mitte', near Velikiye Luki and to the south-west of Orel respectively, was about 350 miles (565 km), the actual length of the front line was about 900 miles (1450 km) excluding some of its many smaller salients and re-entrants. The three most striking features of the new front line were the Toropets bulge, some 150 miles (240 km) deep and at least as wide, in the north; a salient measuring 75 by 125 miles (120 by 200 km) and which had developed out of the previous Sukhinichi bulge in the south; and, between these two, a dogleg projection occupied by Generaloberst Walter Model’s 9^th Army, Generaloberst Hermann Hoth’s 4^th Panzerarmee and Generaloberst Gotthard Heinrici’s 4^th Army.

On the rim of the Toropets bulge, the formations of General Leytenant Maksim A. Purkayev’s 3^rd Shock Army of General Polkovnik Ivan S. Konev’s Kalinin Front were 285 miles (460 km) to the west of Moscow and 50 miles (80 km) to the west of the headquarters of Heeresgruppe 'Mitte' at Smolensk. At Gzhatsk, the 4^th Panzerarmee was within 90 miles (145 km) of Moscow. Rzhev, Vyaz’ma and Bryansk, which commanded the primary road and railway approaches to Moscow from the west, so Heeresgruppe 'Mitte' maintained the possibility of a renewed Germans assault on the Soviet capital. Along a 250-mile (400-km) line from Rzhev to an area to the south of Bryansk, however, the army group had acquired a second front that in effect denied it control of the territory to the east of Smolensk. From the army group boundary north to Bryansk and thence farther to the north toward Roslavl and Kirov, partisan forces generally controlled the wide areas between the roads and railways.

The partisans had been disrupting the rear areas of Heeresgruppe 'Mitte' (and the 4^th Army in particular) from a time soon after 'Barbarossa' had rolled over the area. In January 1942 the partisan forces were strengthened by Soviet airborne troops in the 'Vyaz’ma Airborne Operation' (18 January/18 February 1942) as part of the Battles of Rzhev.It was the Soviet hope that the airborne troops and the partisans would between them be able to secure the area and in the process disrupt the German logistics long enough for the Soviet ground offensive to reach and relieve them. The Soviet offensive involving General Leytenant Mikhail G. Efremov’s (from May General Leytenant Kirill A. Meretskov’s) 33^rd Army and General Leytenant Pavel A. Belov’s I Guards Cavalry Corps failed to advance far enough to effect such a relief, though they remained with the partisans and airborne forces, and the Germans were then able to concentrate their local effort on the destruction of the Soviet troops in their rear.

The area between the railway linking Smolensk and Vyaz’ma and the paved road (Rollbahn) through Roslavl was dominated by Belov’s I Guards Cavalry Corps, airborne troops, partisans and survivors of Meretskov’s 33^rd Army. A patchwork of partisan groups provided almost uninterrupted contact between Belov’s region of superiority and the concentration of partisan groups in the Bryansk area. To the north of the railway linking Smolensk and Vyaz’ma railroad, General Leytenant Ivan I. Maslennikov’s 39^th Army and General Major Grigori T. Timofeyev’s (from 19 May General Major Sergei V. Sokolov’s) XI Cavalry Corps occupied a pocket measuring 30 by 40 miles (50 by 65 km) to the east of the road linking Dukhovshchina and Bely.

By the end of April the 4^th Panzerarmee had tightened its grip on the front to the south of the Rollbahn and at Kirov sufficiently to deny Belov and the Bryansk partisans unhindered contact with Soviet territory, but the 39^th Army still had free access to the outside through a gap, 18 miles (29 km) wide, to the north-east of Bely.

Late in March the 9^th Army proposed, as a smaller-scale alternative to the 'Brückenschlag' operation near Ostashkov, an attack to the west out of the area of Rzhev and Olenino toward Nelidovo. While this would not have achieved much toward the elimination of the Toropets bulge, it would have deprived the Soviet forces in the bulge of a road and rail junction, could have constituted the first element of an offensive toward Toropets, and would have cut the 39^th Army’s lines of communications. By a time early in April this 'Nordpol' (ii) attack in the area of Nelidovo had replaced 'Brückenschlag', which by this time had been seen as unfeasible. However, 'Nordpol' (ii) also had its own difficulties in the form first of the spring thaw and second of the unusually heavy rains which extended the rasputitsa past its usual duration and made the going almost impossible.

In the meantime the 4^th Army had developed its 'Hannover I' operation against the pocket of forces controlled by Belov. Although 'Nordpol' (ii) and 'Hannover I' could not been seen in any real way as combining to constitute a major offensive effort, they were more than Heeresgruppe 'Mitte' could consider for joint implementation in the spring of 1942. The flow of reinforcements to the army group had stopped in March, and as soon as the rasputitsa had started, and Adolf Hitler had begun to reverse the flow as he now saw Heeresgruppe 'Mitte' as the source from which to draw reinforcements for the south sector of the Eastern Front, where he was planning Germany’s main summer offensives of 1942. In the first week of May the headquarters of the 4^th Panzerarmee departed, to be followed by five of the 20 corps headquarters in Heeresgruppe 'Mitte'. Between April and a time early in June, Heeresgruppe 'Mitte' lost 16 divisions, which represented at least 20% of its overall strength and 30% of its armoured strength. In the divisions which remained, moreover, the manpower and other shortages were not to be filled until summer, so the army group’s regiments each had to be reduced from three battalions to two, and its artillery batteries from four guns to three. The surviving Panzer and motorised divisions continued to exist only in name, for most of the armour and trucks which had survived the winter were now awaiting repair or major maintenance, and the army group’s workshops could keep no more than 20% in running condition.

Heeresgruppe 'Mitte' was therefore to be no more than a bystander of the 1942 summer campaign. von Kluge informed his senior subordinates on 18 April that the army group’s watchword had to be economy. Within this stricture, by the middle of May von Kluge had decided that 'Nordpol' (ii) was too ambitious an undertaking for the army group to undertake, and after Hitler, whose interest had been wholly refocused from the centre to the south of the Eastern Front, raised no objection, von Kluge cancelled it and instructed the 9^th Army to work on 'Seydlitz' as a smaller operation against the 39^th Army and XI Cavalry Corps. In the meantime, the 4^th Army was to proceed with 'Hannover I', and when this had been completed the troops used were to be transferred to the 9^th Army for 'Seydlitz'. von Kluge and other senior German commanders believed that 'Hannover I' and 'Seydlitz', being directed against conventional Soviet forces, would follow predictable courses. Experience told von Kluge that operations against the partisan groups around Bryansk promised much less. The area was larger and the anticipated return for the effort certainly would be smaller. Since he also had no more troops to spare, von Kluge gave Generaloberst Rudolf Schmidt’s 2^nd Panzerarmee in the army group’s south one security division and left this army to deal with the partisans in any way it could.

The territory controlled by Belov’s forces extended 80 miles (130 km) from east to west and, at its widest, 40 miles (65 km) from north to south, and comprised almost the entire triangle with its corners at Smolensk, Vyaz’ma and Spas-Demensk. In April and early in May, Belov was engaged in the reorganisation of the partisan, cavalry and airborne troops under his command to comply with orders coming to him from General Georgi K. Zhukov’s West Front, which was planning another drive toward Vyaz’ma as part of the Soviet concept of an active defence. In the less critical western two-thirds of the his pocket, Belov established two partisan divisions; and in his pocket’s eastern one-third, Belov had the cavalry, airborne troops and more partisans. On 9 May, Soviet aircraft delivered in a battalion of anti-tank guns and, with it, General Major Vladimir S. Golushkevich, the West Front’s deputy chief-of-staff, with an order for Belov’s forces to be ready to strike to the south no later than 5 June to meet General Leytenant Ivan V. Boldin’s 50^th Army, which was currently being reinforced with tank corps and would be advancing north across the Rollbahn.

For 'Hannover I', the 4^th Army had the headquarters of General Hans Zorn’s LXVI Panzerkorps and three divisions of Generaloberst Georg-Hans Reinhardt’s 3^rd Panzerarmee, which had taken over the sector of the departed 4^th Panzerarmee, and the headquarters of General Kurt Brennecke’s XLIII Corps and three divisions of its own. These two major formations were, it was believed, more than adequate to cope with Belov’s cavalry and other regular forces, which were estimated at between 10,000 and 20,000 men, but not enough to scour the entire 1,500 sq miles (3885 km²) of the Soviet pocket. Belov’s strength was actually little short of 20,000 men, and included one tank battalion with 18 tanks. Although it had second priority, in terms of its timing, 'Seydlitz' was tactically more urgent than 'Hannover I' as it was essential to the stability of the situation in the Rzhev salient, and in combination with Belov’s presumed deployment, this made a small solution, which could be achieved swiftly, seem worthwhile.

Intercepted Soviet radio transmissions and information from agents and prisoners suggested that Belov had his headquarters and the main strength of his regular troops in the eastern end of the pocket, just to the east of the Ugra river. This estimate was wrong in what was to be one significant respect: while elements of General Major Aleksandr F. Kazankin’s IV Airborne Corps and the 'Zhabo' Partisan Regiment were indeed located to the east of the Ugra river, most of Belov’s cavalry was to the west of the river.

Heeresgruppe 'Mitte' and the 4^th Army opted for a plan which promised to run Belov down in one fast sweep. Two divisions of the XLVI Panzerkorps, striking to the south from the area to the south of Vyaz’ma and one division of the XLIII Corps striking to the north from the Spas-Demensk area, were to pinch off the eastern end of the Soviet pocket, trapping Belov’s main strength to the east of the Ugra river and the railway linking Vyaz’ma and Kirov, which was to be closed off by the advance from the east of Generalleutnant Heinrich Meyer-Bürdorf’s 131^st Division and Generalleutnant Friedrich Fürst’s 34^th Division in the north and south respectively. 'Hannover I' offered no exceptional tactical difficulties and was initially scheduled to start on 21 May, but had to be postponed several times as a result of sustained heavy rain, which turned the ground, still soft from the thaw, back to glutinous and effectively impassable mud: so far as the Germans on the central sector of the Eastern Front were concerned, the appallingly cold weather of the winter of 1941/42 was now being followed by a spring of exception wetness.

Even as it was being planned, 'Hannover I' acquired one decidedly unusual aspect. Late in 1941, at Osintorf near Orsha, the Abwehr (intelligence organisation of the Oberkommando der Wehrmacht) had begun to train several hundreds of captured Soviet officers and men to undertake diversionary activities in the Soviet rear areas. The Germans had experimented earlier with similar groups, but these had been made up of émigrés, members of ethnic minorities, or Russian-speaking Germans, few of whom had lived in USSR recently or had experience of anything but the very edges of Soviet life. With the exception of their commander, the émigré Colonel Konstantin Kromiady, the Osintorf trainees were current and authentic products of the Soviet system, and most especially of the Soviet army. Wearing Soviet uniforms, the trainees could be expected to merge easily into Soviet formations, especially highly mixed forces such as those under Belov’s command. For 'Hannover I', 350 of these men were assigned to the 4^th Army as the Experimental Organisation Centre with the task of disrupting the Soviet defence by finding and killing Belov and his staff or, failing that, undertaking sneak attacks and spreading false orders and disinformation.

On 23 May more heavy rain inundated the area earmarked for the implementation of 'Hannover I', but Heinrici was afraid to lose yet another day and with it the probability of gaining total tactical surprise, and therefore decided to launch 'Hannover I' on the following day. The Experimental Organisation Centre entered the pocket from the south during the night of 23/24 May, and the 4^th Army's formations started to advance during the morning in pouring rain and despite the fact that in several places the men were up to their waists in mud and water. Even so, advancing from the south, Generalleutnant Gustav Schmidt’s 19^th Panzerdivision managed to push 10 miles (16 km) to the north before 12.00 to reach the Ugra river near Vskhody: as the men of the division gained sight of the bridge there, the Soviets blew it, which was probably unnecessary as the water was rising so fast that the bridge would in all probability had been swept away. The division spent the rest of the day establishing a bridgehead to the north of the river and building a pontoon bridge over water that seemed to be rising inexorably. Advancing from the north, Generalleutnant Ehrenfried Böge’s 197^th Division took five hours to reach the station at Ugra, where the railway linking Vyaz’ma and Kirov crossed the river. At this stage an advance of just 10 more miles (16 km) would close the trap on the Soviet pocket. German intercepts of what were perceived to be encrypted messages from Belov’s radio seemed to indicate alarm, if not actual panic. von Kluge congratulated the men, and Heinrici agreed that their performance had been excellent. Heinrici had not expected them to reach Vskhody and Ugra station until the second day of 'Hannover I' as he had anticipated a stronger Soviet defence. At the same time, though, both von Kluge and Heinrici began to suspect that the Soviet resistance their divisions had so far encountered were more typical of partisans than of Soviet regular troops.

The rain, so heavy that even Fieseler Fi 156 Storch tactical reconnaissance aircraft could not get off the ground, continued through the night and the following day, and the Germans became worried as the Ugra river, already 110 yards (100 m) wide, spawned a second channel 22 yards (20 m) wide. For two days the German armour, artillery trucks and infantry came to a halt in mud and water. Given the its lack of air reconnaissance information, the 4^th Army had no idea what the Soviet forces were doing. Although he could not imagine how the Soviets might cross the river’s spate, von Kluge knew that they woulds attempt to do so, and during the afternoon of 25 May instructed Heinrici to angle his spearheads 10 miles (16 km) farther to the west in the direction of Fursovo, on the assumption that the Soviets would indeed have been able to cross the river by then.

Another full day passed without the full completion of the German encirclement, and von Kluge and Heinrici agreed that if Belov had not already done so, he almost certainly would be able to escape to the west, and 'Hannover I would therefore have to be extended into a second phase.

The German spearheads met at Fursovo shortly before the fall of night on 27 May, and mopping-up operations over the next five days, failed to bring either Belov or his main force to action, let alone capture or defeat. Men of the Experimental Organisation Centre, of whom about two-thirds returned, were able to confirm that several Soviet staffs had been in the pocket, including those of Belov, the IV Airborne Corps and the 'Zhabo' Partisan Regiment.

As far as the 4^th Army was concerned, the results of 'Hannover I' up to this time were disappointing: the operation had captured about 2,000 Soviets killed about 1,500 more, but Belov and most of his mean had clearly managed to escape the German net possibly, as revealed by interrogation of prisoners, because Belov had been afforded at least a one-day warning of the offensive from a man who had deserted from the Experimental Organisation Centre. The Soviets had already known of the existence of this unit, but not where it was to be deployed. As a result, according to the prisoners, the mere fact of knowing that the unit was in the area had caused confusion and raised a measure of panic, and members of the Experimental Organisation Centre in fact reported seeing instances of Soviet units firing on each other. Belov later stated that on 23 May, the 8^th Airborne Brigade destroyed a group of 'diversionists' whose mission had been to destroy his staff, and that he learned of the coming German attack from one of this unit’s survivors.

At the end of what the Germans now appreciated was only the first phase of 'Hannover I', Belov still had 17,000 troops and his 18 tanks, but these had been forced to leave the eastern, and tactically most valuable, one-third of the pocket. By this time Belov had come to the conclusion that all hope of linking with Boldin’s 50^th Army was fast disappearing, and on 4 June therefore asked for the authorisation of the West Front to begin the movement of his forces back to the Soviet side of the front. Zhukov gave his permission because the tank corps and reserves for the 50^th Army had by this time been transferred to the area of Kharkov. Belov had three options: to head to the west into Belorussia and convert to partisan operations, to move to the north in the direction of the Kalinin Front, or to move to the south toward the weak spot in the German line at Kirov. The Soviet commander rejected the first two options as they would mean that his forces would lose their significance as regular troops by becoming partisans and as they lacked the means to get their armour and artillery across the Dniepr river, which would have to be crossed if they moved to the north. Belov therefore decided to move to the west toward Yelnya, in the south-west of his pocket, and then head to the south and east into the northern part of the area in which the Bryansk partisans were operating, and thence strike to the east to break back into Soviet-held territory near Kirov.

The newly organised second phase of 'Hannover I' began on 3 June in more still further rain. Heinrici had turned his divisions on the near side of the Ugra pocket around to pursue Belov’s forces to the west in the area between Yelnya and Dorogobuzh, the latter in the north-western part of the pocket, and drive them back against the Dniepr river. It would have been better to have pushed straight through and head off Belov’s forces to the east of the river, but the continuing rain and ubiquitous mud meant that the German infantry could not move fast enough, and the tanks, artillery and trucks could not move at all.

Without ever gaining even the remotest sight of the main Soviet force, the 4^th Army reached Dorogobuzh and Yelnya after five days incredibly hard effort skirmishing with numerous small parties which seemed to be partisan rather than regular forces. Belov was then confined in a pocket measuring 30 by 30 miles (48 by 48 km) blocked on the northern side by the Dniepr river, which was a torrent 220 yards (200 m) wide, and on the south, between Yelnya and the Dniepr river, by the security troops of Generalleutnant Johann Pflugbeil’s 221^st Sicherungsdivision. By this time both von Kluge and Heinrici had started to doubt whether Belov’s regular forces were in the area.

On the morning of 8 June, German pilots over the pocket witnessed an astonishing scene as columns of Soviet tanks, cavalry, airborne troops, trucks and wagons hurried to the south taking any advantage they could of the cover provided by areas of forest. At last the Germans knew where Belov’s main forces were, and that they were preparing to make a break-out attempt. von Kluge ordered a motorcycle battalion to move rapidly from the northern to the southern side of the pocket, and Heinrici took part of Schmidt’s 19^th Panzerdivision from the front in the area to the north of Yelnya to support the 221^st Sicherungsdivision. These reinforcements were too late, however, for during the night the Soviets overran a weak spot in the 221^st Sicherungsdivision's line and simply marched out. After the break of day, German aircraft reported about 1,000 vehicles and large numbers of troops moving into deep forest around the headwaters of the Desna river to the south of Yelnya. When the motorcycle and Panzer units closed the gap later in the day, not much of the Soviet forces was left in the pocket.

After passing Yelnya, Belov’s forces entered the area of the 'Law' Partisan Regiment, where ground troops could not readily pursue him, but where German warplanes bombed the Soviet positions right through the day and returned during the night in an attempt to destroy the Soviet aircraft on the ground after landing to deliver supplies.

Within three days, the 4^th Army had established a screening line along the Rollbahn, which Belov’s forces would have to cross if they were to make their way toward Kirov. In the meantime, Belov’s forces had halted in the forest near Klin, about mid-way between Yelnya and the Rollbahn, to reorganise and receive supplies delivered by aircraft. After another two days, the Germans began to believe that Belov’s forces might once again have disappeared. Signal intercepts suggested that Belov himself was still operating near Klin, but deserters said he had been flown out and that his forces were dissolving into smaller parties. Finally, just before 24.00 on the night of 15 June, Belov reappeared, where he had been expected, on the Rollbahn.

There is disagreement between the German and Soviet accounts of the events which now began. Belov himself said that the Soviet break-out was to have been made in two echelons, with General Major Viktor K. Baranov, commander of 1^st Guards Cavalry Division, leading the first and Belov himself the second. When Baranov emerged from the woods a short distance to the north of the Rollbahn, from several hundred yards to the rear Belov heard shouting as the cavalry charged and crossed the road, but soon discovered that the first echelon’s infantry had not been able to do so. In his own account, Belov says that he reassembled the 2^nd Guards Cavalry Division and elements of the IV Airborne Corps and 329^th Division, and then pulled back into the woods. On the following day, according to Belov, this grouping emerged from the woods about 10 miles (16 km) to the north of the Rollbahn, made a wide sweep to the west and then to the south, and thereby crossed the road 10 miles (16 km) to the east of Roslavl.

The German accounts reported three simultaneous Soviet attacks, one of them headed by a general on horseback, whom the Germans took to have been Belov. The first reports indicated that more than 3,000 Soviets had broken out. Heinrici could believe that so many men could have passed through three small gaps left open for less than one hour, and therefore came to the conclusion that, whether Belov had escaped or not, most of his men must still be in the area to the north of the road. Patrols probing into the pocket during 16 June discovered Soviets, but could not establish their numbers. Deserters said there were between 8,000 and 10,000 men, but the 4^th Army believed that 6,000 was more probable.

During the afternoon of 18 June, a patrol found a dead Soviet officer carrying an order dated on the previous day and signed by Belov. This gave detailed directions for a mass break-out across the Rollbahn and set the time for 24.00 on the same day. The Germans appreciated that the order could be an attempted deception, but knew nonetheless that Belov would have to make his move soon as the ring was closing on what was left of his forces. With no other information on which to work, the 4^th Army swiftly established three lines on the section of the Rollbahn specified in the Soviet order, one of them on the road and the other two farther back.

Earlier experience had shown the Germans a single line could not halt the charge of thousands of men, and that if the attack came at any other place it would probably succeed. But the Soviet effort did not materialise elsewhere, and indeed started exactly on time and straight into the fields of fire of the German artillery and machine guns. Fighting continued until after the break of day. About 1,500 Soviets managed to cross the first line, 500 got across the second, and only a few across the third. The other Soviets were driven back into the forest, and at 12.00 on the following day, in the belief that Belov had made his final effort, Heinrici gave the order for his formations to drive into the pocket. By the fall of night, the pocket had been reduced to an area measuring 1.5 by 3 miles (2.4 by 4.8 km). At this juncture it began to rain once more. An infantry company left a gap in the line, and Belov marched out with what the 4^th Army later estimated to have been between 2,000 and 4,000 men.

The Soviets were moving once more, and the Germans were exhausted. In the afternoon of 21 June von Kluge recognised the exhaustion of the 4^th Army, however, and ordered Heinrici to end 'Hannover I' so that his men could rest.

The two phases of 'Hannover I' claimed 10,500 Soviets killed and 20,000 taken prisoner. How many of these were Belov’s troops and how many partisans or civilians was not estimated. Radio intercepts revealed that there was still a radio transmitter, believed to be that of Belov, operational in the forest to the north of the Rollbahn up to the end of the month, but Belov himself said that he had been evacuated by air to the 10^th Army on the night of 23 June, that 10,000 of his men later crossed the front line near Kirov, and that 3,000 more were evacuated by air. A Soviet official history states merely that 'some' of Belov’s force crossed the lines at Kirov and to the north-east of Smolensk during July, while others stayed to fight as partisans. 'Hannover I' cleared Heeresgruppe Mitte's rear areas and also very considerably improved the German line at the cost of about 2,200 casualties.

The partisan forces in the area of 'Hannover I' had been so thoroughly shattered that the Soviets were unable to recreate any significant partisan activity in this region for the remainder of the war. 'Hannover I' is therefore regarded as the most successful German anti-partisan operation ever mounted on the Eastern Front, though the Soviet strength also included large numbers of regular troops, and this is attributable primarily to the fact that the partisans decided to challenge the German forces in open battle.