The Polish garrison of the city (commanded by Smolensk Voivode Filip Obuchowicz) hoped to get reinforcements from the army of Janusz Radziwiłł (1612–1655), stationed in Orsha.

Its situation worsened when Radziwiłł suffered a defeat from Prince Yakov Cherkassky in the Battle of Shklow.

In September, the Polish garrison agreed to leave the city after it was promised a free retreat.

The garrison left Smolensk and handed over its weapons and ensigns to the Russians before retreating to the Commonwealth-controlled territory.

A significant number of landowners, however, preferred to stay and keep their estates, becoming subjects of the Russian Tsardom.