Firstly, Timoshenko paused the offensive, in order to reorganize and resupply the Soviet forces. One of the first thing he did was to narrow the frontage of the 7th Army -- made it responsible for facing the Mannerheim Line only. He brought the 13th Army to cover Lake Ladoga. he planned to advance the 13th Army across the frozen lake. finally, he made sure to establish deep-echeloned forces, in order to be able to sustain assaults.
He then launched an offensive in february 1940. Unlike his predecessor Voroshilov had done, he concentrate most of artillery onto the Mannerheim Line. he also massed tanks to protect 7th Army's infantry as they stormed the line. The 13th Army advanced across the frozen Ladoga.
At the end ( Thanks to Timoshenko ), the Soviets overwhelmed the Finns with concentric attacks, forcing the Finns to face the Soviets along the static front of the Mannerheim Line and Lake Ladoga, and forcing the Finns under relentless pressure (while the Soviets had deep-echeloned forces to continue attacking, the Finns did not), thereby lessening the Finnish tactical superiority.
If Voroshilov wouldnt have been replaced by Timoshenko, the outcome of the war might have been wery difrent.
