Short answers, pulled from the story.
The second Smolensk operation began on the 7th of August 1943 and lasted until the 2nd of October 1943. This offensive cleared German forces from the Smolensk and Bryansk regions over a two-month period.
Soviet troops included the 39th, 43rd, and 10th Guards armies along with the 5th Army and 68th Army to execute the initial push toward Roslavl. General Andrei Yeremenko commanded the Kalinin Front while Vasily Sokolovsky led the Western Front during these operations.
Mechanized troops encountered significant difficulties due to swamps, forests, ravines, and heavy rainfall that turned roads into mud known as rasputitsa. The terrain featured hills over one hundred meters high and few bridges or ferries across wide rivers like the Dnieper and Western Dvina.
German forces built extensive defensive positions numbering five or six lines in some places covering a total depth of several kilometers. These lines included three sets of trenches linked by communication networks, barbed wire, minefields, and antitank moats on elevated ground.
The operation tied down up to forty percent of all Wehrmacht divisions near Smolensk which prevented critical reinforcements from crossing the Dnieper in the south. It removed a strategic threat to Moscow approaches since 1941 while weakening German defenses further north.