'Seydlitz' (iii) was a German offensive by Generaloberst Heinrich-Gottfried von Vietinghoff-Scheel’s 9^th Army between Olenino and Bely in the west, and Rzhev, Sychevka and Vyaz’ma in the east (2/12 July 1942).

In the aftermath of the Soviet winter counter-offensives of 1941/42, substantial Soviet forces remained in the rear of the 9^th Army, and maintained a hold on the forested swamp region between Rzhev and Bely. 'Seydlitz' (iii) was planned and executed to clear the Soviet forces from the area: the Germans first blocked the natural break-out route through the Obsha river valley and then split the Soviet forces into two isolated pockets. The battle lasted 11 days and ended with the destruction of the encircled Soviet forces.

The operation was undertaken as part of the general improvement of the German line in the areas to the west of Moscow, which had been turned into a massive series of eccentric salients and re-entrants by the Soviet winter offensive of 1941/42. The westward-facing Soviet salient in the area of Bely, just to the west of Sychevka, had been created between January and April 1942 by the offensive of General Polkovnik Ivan S. Konev’s Kalinin Front against Generalfeldmarschall Günther von Kluge’s Heeresgruppe 'Mitte'. The Soviets had driven a great salient toward Smolensk, but this had been divided into halves by the counter-offensive launched in the direction of Bely by Generaloberst Hans-Georg Reinhardt’s 3^rd Panzerarmee. The eastern half was now held by General Leytenant Ivan I. Maslennikov’s 39^th Army supported by General Major Sergei V. Sokolov’s XI Cavalry Corps, and von Kluge decided that the 9^th Army should destroy the salient, so shortening the German defence line by 130 miles (210 km). As well as improving the German line and so permitting a reduction in the number of divisions required to hold it, the elimination of the salient would net the Germans large numbers of Soviet prisoners and considerable quantities of matériel.

For the summer campaign season of 1942, Heeresgruppe 'Mitte' was to play only a secondary role as the primary German effort was to be made in the 'Blau' offensives farther to the south. von Kluge, the army group commander, informed his subordinate commanders on 18 April that the army group had to economise on the forces it still possessed. By the middle of May, Kluge had become convinced that the proposed 'Nordpol' plan was too ambitious and, in the absence of any objection by Adolf Hitler, whose interest had shifted completely away from the area, von Kluge cancelled 'Nordpol' and ordered the 9^th Army to work on 'Seydlitz' (iii), a smaller operation directed against Maslennikov’s 39^th Army and Sokolov’s XI Cavalry Corps. In the meantime, General Gotthard Heinrici’s (from 6 June General Hans von Salmuth’s) 4^th Army would go ahead with 'Hannover I' and, when this had been completed, transfer some of its troops to the 9^th Army for 'Seydlitz' (iii). As they were directed against conventional Soviet forces, 'Hannover I' and 'Seydlitz' (iii) could be expected to take reasonably predictable courses. Experience had confirmed in von Kluge’s mind the fact that operations against partisan forces in the area round Bryansk promised much less: the ground to be covered was larger, and the anticipated return for the effort would undoubtedly be smaller. Given, moreover, that he had no more troops to spare, von Kluge gave Generaloberst Rudolf Schmidt’s 2^nd Panzerarmee one security division and left the army to deal with the partisans as best it could.

For 'Hannover I', the 4^th Army had a corps headquarters and three divisions from Reinhardt’s 3^rd Panzerarmee, which had assumed control of the sector of the front previously held by Generalobrst Hermann Hoth’s 4^th Panzerarmee, and one corps headquarters and three divisions of its own. These forces were sufficient to cope with the cavalry and other regular troops, estimated at between 10,000 and 20,000 men, of General Major Pavel A. Belov’s I Guards Cavalry Corps, but insufficient to scour the entirety of the 1,500-sq mile (3885-km²) Soviet pocket. Despite the fact that it had second priority in terms of timing, moreover, 'Seydlitz' (iii) was more urgent in tactical terms as it was essential to the stability of the German position in the Rzhev salient.

'Seydlitz' (iii) had nonetheless to await the completion of 'Hannover I' and 'Hannover II' before it received a corps headquarters, two divisions, and the required air support. The delay provided useful time for planning, and 'Seydlitz' (iii) therefore passed through several revisions. In the final version, von Kluge and von Vietinghoff-Scheel, who had replaced Generaloberst Walter Model as commander of the 9^th Army while the latter was in hospital recovering from a wound, opted for a pair of thrusts, each by one Panzer division backed by one infantry division, to close the Bely gap on the north-western shoulder of the XI Cavalry Corps' pocket, while single Panzer divisions made two other assaults from the area to the south of Olenino and to the east of Sychevka to split the 39^th Army. The second two assaults depended on Generalleutnant Gustav Fehn’s 5^th Panzerdivision, which was engaged in 'Hannover', and Generalmajor Walther Düvert’s 20^th Panzerdivision, which was to be detached from the 3^rd Panzerarmee slightly farther to the south. Four infantry divisions would hold the perimeter, and Generalleutnant Heinrich Wosch’s 14^th Division (mot.) would be the reserve. 'Seydlitz' (iii) was therefore to involve no fewer than 11 German divisions, but despite the fact that these were rested and recovered from the winter, they were all very considerably below strength for lack of adequate numbers of replacements.

The operation also faced a pair of hazards would could not be offset by any amount of planning. One was, of course, the weather, which continued very wet throughout June, and the other was the Soviet intentions. Other than the fact that the 39^th Army and XI Cavalry Corps were located somewhere in an expanse of forest measuring 40 by 60 miles (65 by 100 km) between Bely and Sychevka, nothing of value was known of them for, like Belov’s force, they had virtually disappeared with the melting of the winter snow.

'Seydlitz' (iii) started early in the morning of 2 July, shortly after 24.00, which at that time of year is only about two hours before dawn. von Kluge’s command train was parked at Sychevka, and he and von Vietinghoff-Scheel were behind Generalleutnant Friedrich Kirchner’s 1^st Panzerdivision, backed by Generalleutnant Johannes Friessner’s 102^nd Division, on the northern side of the Bely gap. The first day of the operation resulted in two major shocks: the 1^st Panzerdivision made almost no headway, and what appeared to be several dozen Soviet tanks were reported to be moving toward the flank of Generalleutnant Hans-Karl von Esebeck’s 2^nd Panzerdivision, backed by Generalleutnant Ehrenfried Böge’s 197^th Division, in the area to the north-east of Bely on the southern side of the Bely gap. By the end of the day, both prongs of the German attack had been brought to a halt, and that in the south was having to ready itself to face a counterattack.

During the morning of the following day, after ground and air reconnaissance had reported that there were more than 50 Soviet tanks heading toward Bely, von Kluge approved a change in the plan to turn the 5^th Panzerdivision from the south to the west along the course of the Obsha river to bring it out in the area to the north-east of Bely behind the Soviet armoured force. But the 5^th Panzerdivision was fighting through dense forest and had not yet reached the Obsha river, and at the end of the day 'Seydlitz' (iii) was stalled at every point. The war diary of the 9^th Army noted on 3 July that severe and fluctuating battles were to be expected in the coming days and weeks.

The morning of 4 July brought more discouragement: the 1^st Panzerdivision was still unable to advance, Soviet armour was making headway into the 2^nd Panzerdivision's flank from the east, and von Vietinghoff-Scheel had to commit the 14^th Division (mot.) to aid the 5^th Panzerdivision in resuming its advance. During the day, however, there was a radical change in the situation. The 20^th Panzerdivision, supported on its north and southern flanks by Generalleutnant Joachim von Tresckow’s 328^th Division and Generalleutnant Bogislav von Studnitz’s 87^th Division, began its push toward the west from its position to the south-west of Sychevka and met almost no opposition. By the fall of night, the 1^st Panzerdivision had got under way once more and advanced 6 miles (10 km) and the 5^th Panzerdivision was turning into the Obsha river valley, leaving the 14^th Division (mot.) to press ahead toward the south. One day later, the 1^st Panzerdivision had closed the Bely gap, and the 5^th Panzerdivision and 20^th Panzerdivision were advancing to the east to split the Soviet pocket into three. Yet to be answered, however, was the location of the 39^th Army and XI Cavalry Corps. The Soviet tank attack had seemed to indicate that they were massed in the north, ready to break out, but by the fourth day, it seemed that they were planning to emulate Belov and his mixed force of regular troops and partisans by disappearing into the forest.

During the morning of 6 July, though, the answer became evident when the 9^th Army's intelligence branch deciphered an intercepted radio message ordering all formations and units of the 39^th Army to pull back toward the north-west. By this time the forest’s clearings were filling with columns of Soviet troops, and it was clear that the 39^th Army was, after all, about to attempt a break-out. Depending on how far to the north and west they were, though, the army’s constituent elements would have to cross one, two or even three German lines. During the afternoon, the 5^th Panzerdivision passed through the Obsha river valley and 197^th Division, pushing to the east, met the the leading units of the 20^th Panzerdivision.

As dawn appeared on the following day, aerial reconnaissance over the southern loop of the Soviet pocket sighted a long column of armour, cavalry and infantry, and it was evident that the XI Cavalry Corps was also now out in the open and, much to the surprise of the 9^th Army, moving to the north, where the 20^th Panzerdivision was situated.

'Seydlitz' (iii) was over. With all transport routes blocked both in front and behind them, the Soviet columns became ever more compressed and entangled with each other. As the German divisions closed on the mass of Soviet men, aircraft dropped one million leaflets informing the troops how to surrender. By 10 July most of the Soviets seemed to be waiting to be rounded up, and on 12 July von Vietinghoff-Scheel declared 'Seydlitz' (iii) to be complete. On that day the prisoner tally was 25,000 men, and one day later 37,000 men, 220 tanks and 500 pieces of artillery. The 9^th Army had estimated the total strength of the 39^th Army and XI Cavalry Corps at about 50,000 men, and while the Germans had no illusions about the fact that there were still several thousand men still free in the forests, the 39^th Army and XI Corps had been destroyed.

During August, the Soviet partisans of the area issued a proclamation in the area in which 'Seydlitz' (iii) had been fought, this urging all men of the armed forces who had escaped from the pocket to attempt to rejoin their units or otherwise join the partisan ranks. Those who remained in hiding merely to save their own lives and those who did not the 'Great Patriotic War' to help destroy the German 'robbers', and those who deserted to the 'Fascist' army and helped carry on the 'robber' war against the Soviet people, were traitors to the homeland and would be liquidated sooner or later.