The 'Smolensk-Roslavl Offensive Operation' was fought by the Soviet forces of General Vasili D. Sokolovsky’s West Front, supported on its right flank by elements of General Andrei I. Eremenko’s Kalinin Front, against Generaloberst Generaloberst Georg-Hans Reinhardt’s 3^rd Panzerarmee of Generalfeldmarschall Günther von Kluge’s Heeresgruppe 'Mitte' as part of the six-part 'Suvorov' (otherwise the 'Smolensk Strategic Offensive Operation') (15 September/2 October 1943).

By the middle of 1943, the situation on the Eastern Front had changed as the Soviets, now possessing the strategic initiative, initiated started a general offensive along almost its total length, beginning with the 'Belgorod-Kharkov Strategic Offensive Operation' (otherwise 'Polkovodets Rumyantsev' of 3/23 August) and the 'Orel Strategic Offensive Operation' (otherwise 'Kutuzov' of 12 July/18 August) in the aftermath of the German defeat in the Battle of Kursk ('Zitadelle'). These were followed by Germany’s defensive Battle of the Dniepr River in northern Ukraine. Despite the significance and scale of these undertaking along the southern half of the East Front, Germany was still reinforcing its troops around the more northerly areas round Smolensk and Roslavl, in the process redeploying several divisions from the Orel sector. As a result, the two Soviet counter-offensives that followed the 'Kursk Strategic Defensive Operation' of 5/23 July) proceeded relatively easily for the USSR in the Orel region, creating a large salient in the area to the south of Smolensk and Bryansk.

In this situation, the former Soviet primary attack axis, directed south-west toward Roslavl and Bryansk, became useless, and the Stavka accordingly decided to shift the axis to the west toward Yelnya and Smolensk. The 'Yelnya-Dorogobuzh Offensive Operation' was now seen as the key to Smolensk. The Germans appreciated this fact, and had for some time been creating a massive series of fortified defensive positions around the city: swampy areas on the Desna and Ugra rivers were mined and heavy artillery was sited on the hills overlooking the city.

In the week of 7/14 September, Soviet troops were once again reinforced and were preparing for another offensive. The next objectives set by the Stavka were the major cities of Smolensk, Vitebsk and Orsha. The operation resumed on 15 September with the 'Smolensk-Roslavl Offensive Operation', involving the West Front and the left flank of the Kalinin Front. The primary forces committed to he operation were, from north to south, the 4^th Shock Army, 43^rd Army, 39^th Army, 31^st Army, 68^th Army, 5^th Army, 10^th Guards Army, 33^rd Army, 21^st Army, 49^th Army, 10^th Army and 5^th Army.

Following a preliminary artillery bombardment, Soviet troops succeeded in breaking through the German lines.

On the Kalinin Front’s sector, the Soviet forces created a salient 18.5 miles (30 km) wide and between 1.9 and 8.1 miles (3 and 13 km) deep by the end of the first day. After four days of battle, Soviet infantry divisions had captured Dukhovshchina, another perceived 'key' to Smolensk, in the neighbouring '2^nd Dukhovshchina-Demidov Offensive Operation'.

On the West Front’s sector, where the offensive started one day later, the breakthrough was also promising as the initial onslaught had created a salient 12.5 miles (20 km) wide and 6.2 miles (10 km) deep. On the same day Yartsevo, an important rail nexus near Smolensk, was liberated by Soviet troops. On the West Front’s left flank, infantry divisions reached the Desna river and made an assault crossing, creating several bridgeheads on its western bank.

As the result, the German defence line protecting Smolensk was overrun, rendering the German troops defending the city vulnerable to envelopment. General Kurt von Tippelskirch, recently a command of the 4^th Army, later wrote that 'the forces of the Soviet West Front struck the left wing of Heeresgruppe 'Mitte' from the line linking Dorogobuzh and Yelnya with the aim of achieving a breakthrough in the direction of Smolensk. It became clear that the salient -projecting far to the east – in which the 9^th Army (to the south of the 4^th Army') was positioned could no longer be held.'

By 19 September, Soviet troops had driven a gap, 155 miles (250 km) wide and 25 miles (40 km) deep, though the German. On the following day, the Stavka ordered the West Front to drive its forces through to Smolensk by 27 September at the latest, and then to advance toward Orsha and Mogilev. The Kalinin Front was ordered to capture Vitebsk by 10 October.

On 25 September, after an assault crossing of the Severnyi Dniepr river and street fighting that continued right through the night, Soviet troops completed the liberation of Smolensk. On the same day another important city, Roslavl, was recaptured. By 30 September, the Soviet offensive force were much depleted by losses and were also exhausted, and became bogged down outside Vitebsk, Orsha and Mogilev, which were still held by the Germans, and on 2 October the 'Smolensk Strategic Offensive Operation' was brought to an end. A limited follow-on operation took Nevel after two days of street fighting.

Overall, Soviet troops had advanced between 62 and 112 miles (100 and 180 km) in a period of almost 20 days of this third part of the offensive.

The 'Smolensk Strategic Offensive Operation' was a huge Soviet victory and a staggering defeat for the Germans. Although quite modest compared to later offensive operations, the Soviet advance during this operation was important for several reasons. Firstly, the German forces had been definitively driven back from the approaches to Moscow: this strategic threat, which had been the Stavka’s greatest concern since 1941, had finally been removed. Secondly, the German prepared defensive lines, on which Adolf Hitler and senior commanders had placed their operational faith, had been almost totally overrun, and while some remained, it was clear that none of these could survive. Thirdly, the 'Smolensk Strategic Offensive Operation' had provided major support to the 'Donbass Strategic Offensive Operation' (13 August/22 September) and the 'Lower Dniepr Strategic Offensive Offensive' (26 September/20 December) by pinning down between 45 and 55 divisions near Smolensk and thus preventing their redeployment to the southern end of the Eastern Front. Fourthly, a once-unitary German front was now split into two by the huge and impassable Pripyet marshes, isolating Generalfeldmarschall Erich von Manstein’s Heeresgruppe 'Süd' from its northern counterparts, thus greatly reducing Germany’s ability to shift troops and supplies from one sector of the front to the other.

For the first time, Soviet troops re-entered territories which had been occupied for a long time by the Germans, and started to discover the extent of war crimes committed by SS-Einsatzgruppen and other elements of the SS and army. In the areas liberated during the Smolensk operation, almost all industry and agriculture had disappeared. In the Smolensk region itself, almost 80% of urban and 50% of rural living space had been destroyed, along with numerous factories.

After the Smolensk offensive, the central part of the Eastern Front stabilised again until a time late in June 1944 as the major fighting shifted to the south to the struggle for the Dniepr river line and Ukraine. Only during January 1944 was the front to move again in the north, when German forces were driven back from Leningrad, completely lifting the siege which had lasted for 900 days. Finally, 'Bagration' during the summer of 1944 allowed the Soviets to clear the Germans out of almost all Soviet territory, thus ending German occupation and shifting the war into Poland and Germany.