3 months, Winter '39-'40. 126,875–167,976 Soviet dead or missing, 188,671–207,538 wounded or sick. [Colorized]

"Before the war, Soviet leadership had expected total victory within a few weeks. The Red Army had just completed the invasion of eastern Poland at a cost of fewer than 4,000 casualties after Germany attacked Poland from the west. Stalin's expectations of a quick Soviet triumph were backed up by politician Andrei Zhdanov and military strategist Kliment Voroshilov, but other generals were more reserved."

No, no, those other generals have a point