The 'Vyaz’ma Defensive Operation' was the second of the seven sub-operations that together constituted the 'Moscow Strategic Defensive Operation, and as such was the northern counterpart of the 'Orel-Bryansk Defensive Operation' as the Soviets attempted to prevent the German forces of Generalfeldmarschall Fedor von Bock’s Heeresgruppe 'Mitte' from the envelopment of Moscow from the south and north (2/13 October 1941).

The two major Soviet formations involved in this undertaking were General Polkovnik Ivan S. Konev’s (from 10 October General Georgi K. Zhukov’s) West Front and Marshal Sovetskogo Soyuza Semyon M. Budyonny’s Reserve Front (up to 30 July Front of Reserve Armies). The parallel Soviet defensive undertakings were the first steps in the 'Great Patriotic War' to counter the German 'Taifun' (i), and both ended in complete Soviet disasters as the German swept forward an encircles whole Soviet armies for destruction and the capture of vast numbers of men, leaving no Soviet troops left in front of Moscow, and triggering in the capital a massive panic that lasted for several days.

In the 'Vyaz’ma Defensive Operation', the forces of Heeresgruppe 'Mitte' managed to break through the Soviet defences and encircle four armies in the area to the west of Vyaz’ma: these four armies comprised 37 infantry divisions, nine tank brigades and 31 artillery regiments. The Soviet losses, in terms of men killed and wounded, were more than 380,000 men and, in terms of men taken prisoner, more than 600,000 men. The total irrecoverable Soviet losses amounted to more than one million people, and the German success left open the road to Moscow. The Soviet high command took emergency measures to strengthen the 'Mozhaysk Defence Line' and shore up the shattered front, throwing poorly armed units of militia men and military school cadets against the German armoured divisions.

After carrying out a major regrouping of its forces during the second half of September 1941, the German command concentrated its main forces against the formation of the Soviet Western Direction in the expectation that it would achieve the objects of the autumn campaign and a secure a favourable outcome to the war as a whole by defeating the most powerful grouping of Soviet troops. Within this, the offensive toward Moscow was codenamed 'Taifun' (i). This ordained that Heeresgruppe 'Mitte' would strike in three directions, divide the Soviet front into separate segments, encircle and destroy the forces of the West Front and Bryansk Front in the areas of Vyaz’ma and Bryansk while not allowing any escape to Moscow, and then crush the Soviet defenders on the near approaches to Moscow and so facilitate the seizure of the Soviet capital.

As it planned an offensive against the West Front within the context of 'Taifun' (i), the German high command assumed that the use of massive blows from the regions of Dukhovshchina and Roslavl in the general direction of Vyaz’ma would break through the Soviet defences, encircle and destroy whole Soviet armies in the area of Vyaz’ma, and finally develop an offensive on Moscow. To achieve this goal, the main forces of Heeresgruppe 'Mitte' were allocated. Generaloberst Adolf Strauss’s 9^th Army, concentrated in the area of Dukhovshchina and with Generaloberst Hermann Hoth’s 3^rd Panzergruppe subordinated to it, had the task of reaching the line lining Vyaz’ma and Rzhev, covering Vyaz’ma from the north and east. Generalfeldmarschall Günther von Kluge’s 4^th Army was concentrated in the area of Roslavl with Generaloberst Erich Hoepner’s 4^th Panzergruppe subordinate to it, had the task of advancing along the Varshavskoye highway with an exit to Spas-Demensk and then wheeling to the north toward Vyaz’ma in order to encircle the West Front’s main forces.

By the beginning of the operation, the Germans had been able to mislead the Soviets about the direction of their planned primary strikes and, having regrouped, had thus been able to create a numerical superiority in the selected areas including in the Dukhovshchina area (3/1 in men, 1.7/1 in tanks and 3/8/1 in pieces of artillery and mortars) and in the Roslavl area (3/2/1 in men, 8.5/1 in tanks and 8.5/1 in pieces of artillery and mortars).

The headquarters of the West Front appreciated that the Germans were about to take the offensive, but concentrated its main strength along the road linking Smolensk and Vyazma on the junction of General Leytenant Konstantin K. Rokossovsky’s 16^th Army and General Leytenant Mikhail F. Lukin’s 19^th Army armies: this was an error as the Germans struck not along the road but at points to the north and south of it.

On 1 October, the West Front had the 22^nd, 29^th, 30^th, 19^th, 16^th and 20^th Armies with 32 infantry divisions, two motorised infantry divisions, three cavalry divisions, four fortified areas, the 126^th, 127^th, 128^th, 143^rd and 147^th Tank Divisions and one mechanised brigade: these totalled 320,000 men, 475 tanks, 2,253 pieces of artillery, 733 mortars and 272 aircraft. The front’s troops were deployed in a single echelon holding defences which extended along a 210-mile (340-km) line to the east of Andreapol, east of Yartsev and west of Yelnya. The front-line reserve contained two cavalry divisions, the 101^st Motorised Division and the 126^th, 128^th, 143^rd and 147^th Tank Brigades as well as a number of other units. The density of these first-echelon troops was 9.33 miles (15 km) per division, while those of the tanks was 1.6 per kilometre, of the artillery and mortars 7.5 per kilometre, and of the anti-tank guns 1.5 per kilometre.

The Reserve Front had the 24^th, 31^st, 32^nd, 33^rd, 43^rd and 49^th Armies with 16 infantry divisions, 12 people’s militia divisions, four tank divisions, two cavalry divisions, one fortified area and one tank brigade. These were deployed in two echelons with the 24^th Army and 43^rd Army located forward in the Roslavl area along the line of the Desna river from the area to the west of Yelnya to the railway connecting Roslavl and Kirov in a strip up to some 60 miles (100 km) in width. Three of the Reserve Front’s other forces (31^st, 49^th and 32^nd armies) took up defensive positions in the West Front’s rear along the line linking Selizharovo, Olenino and Dorogobuzh in a 135-mile (220-km) zone some 30 to 50 miles (50 to 80 km) east of the front edge of the first line of defence The Reserve Front last major component was the 33^rd Army, and this constituted the front reserve: it was located in the Spas-Demensk area behind the 24^th and 43^rd Armies. The Reserve Front’s troop density was 6.95 miles (11.2 km) per division, while those of the tanks were 0.9 per kilometre, of the guns and mortars 6.7 per kilometre, and of the anti-tank guns 1.9 per kilometre.

In overall terms, the defences of the West Front and Reserve Front were too focal, shallow (9.33 to 12.5 miles/15 to 20 km), and poorly prepared in field fortifications.

On the German side, the 9^th Army and the 3^rd Panzergruppe possessed three Panzer, two motorised and 18 infantry divisions, whose operational formation was in a single echelon that made it possible to achieve a high density of troops, in the order of one division per 2.1 miles (3.2 km). The 4^th Army and the 4^th Panzergruppe had five Panzer, two motorised and 15 infantry divisions, whose operation formation was in two echelons. All the Panzer and motorised divisions, as well as 10 infantry divisions, were concentrated in the direction of the main strike in a deployment 34.8 miles (56 km) wide, which provided an high density of one division per 2.1 miles (3.3 km).

It was during the morning of 2 October that the main forces of Heeresgruppe 'Mitte' went over to the offensive along the axes toward Dukhovshchina and Vyaz’ma using the 9^th Army, with the 3^rd Panzergruppe on its right, across the whole of the 30^th Army’s front and in the sector of the 244^th Division of the West Front’s 19^th Army Army of the Western Front, and along the axes toward Roslavl and Vyaz’ma using the 4^th Army, with the 4^th Panzergruppe in its right, across the whole of the 43^rd Army’s front. On this day, the Germans broke through the defences of the Soviet forces in the Dukhshchinsky and Roslavl areas and penetrated to a depth of 9.33 to 18.6 miles (15 to 30 km). By the end of the day, the 4^th Panzergruppe's divisions had hit the second echelon of the Reserve Front in the form of the 33^rd Army. German warplanes made two attacks on the West Front’s headquarters, and this led to a partial loss of command and control.

By 3 October, the depth of the German advance against the West Front was as much as 31 miles (50 km) and against the Reserve Front as much as 50 miles (80 km). In order to check the German breakthrough in the area of the 30^th Army, the West Front created an operational grouping (centred on the 152^nd Division, the 101^st Motorised Division and the 126^th, 128^th, 143^rd and 147^th Tank Brigades) under the command of General Ivan V. Boldin. This counterattacked on 3/5 October in the area of Kholm and Zhirkovsky, tackling General Georg-Hans Reinhardt’s (from 6 October Generalleutnant Otto Ottenbacher’s XLI Corps and General Erich von Manstein’s LVI Corps (mot.) of the 3^rd Panzergruppe, and was soundly repulsed.

On 4 October, on the axis toward Roslavl, the 4^th Army and the 4^th Panzergruppe penetrated the the 43^rd Army and 33^rd Army of the Reserve Front to reach the line linking Yelnya, Spas-Demensk and Mosalsk, and by the end of this day had effectively enveloped a grouping of the 19^th Army, 16^th Army and 20^th Army of the West Front and the 32^nd Army, 24^th Army, and 43^rd Army of the Reserve Front. Thus there emerged the very real possibility that German armoured forces would enter the Vyaz’ma region from the north and the south.

On 5 October, the Soviet supreme command approved the decision of the West Front’s commander to withdraw his forces to the defence line linking Rzhev and Vyaz’ma, and reassigned the 31^st Army and 32^nd Army to this front. On 6 October, the Soviet command issued the withdrawal order, but effecting this movement proved impossible in conditions of fierce fighting and partial loss of control. The 16^th Army did manage to fall back, and this transferred its troops to the 20^th Army and 19^th Army for the task of organising the defence of the Vyaz’ma area.

On 7 October, the Germans used the LVI Corps (mot.) of the 3^rd Panzergruppe from the north, and General Hans Zorn’s XLVI Panzerkorps and General Georg Stumme’s XL Corps (mot.) of the 4^th Panzergruppe from the south and east to break through to Vyaz’ma and surround 19 infantry divisions and four tank brigades of the 19^th, 20^th, 24^th and 32^nd Armies, as well as Boldin’s operational grouping, in the so-called Vyaz’ma 'cauldron'. The encircled troops fought stubbornly until 23 October, pinning significant German forces. Some of the encircled Soviet forces broke out of the 'cauldron' on 12 October and fought their way back to the 'Mozhaysk Defence Line'. On the right wing of the West Front, the 22^nd, 29^th and 31^st Armies had by 10 October occupied the line linking Ostashkov, Yeltsy and Sychevka, transferring seven divisions to the 'Mozhaysk Defence Line'.

On 10 October, those elements of the West Front and Reserve Front that had not been surrounded, were united into the West Front, now commanded by Zhukov.

The 'Vyaz’ma Defensive Operation' had thus failed as the Germans broke through the Soviet army’s defensive front to the operational depth to which they had originally aimed, and after destroying much of the West Front and Reserve Front neared the 'Mozhaysk Defence Line' in front of Moscow, thereby creating the situation for a further offensive against the Soviet capital.

According to German data, in the 'cauldrons' near Bryansk and Yelnya, the Soviets lost more than 600,000 men taken prisoner, while the Soviets admitted the loss of about 688,000 men taken prisoner, only about 85,000 men managing to escape from the encirclement. The dead (killed or died of wounds) was in the order of 200,000 to 275,000 men, 120,000 to 150,000 men wounded or taken ill, and between 450,000 and 500,000 men missing or taken prisoner. The total losses of the West Front, Reserve Front, field construction elements and a number of civilian commissariats was between 770,000 and 925,000 people.