Editing Winter War (section)

===Red Army reforms and offensive preparations===
[[File:Inspecting Soviet skiing manuals.jpg|thumb|alt=Four Finnish officers in uniform are sitting and reading Soviet skiing manuals with relaxed looks on their faces. A pile of the books is in front of them on a table, and a large drape of [[Joseph Stalin]] hangs above their heads on the wall.|Finnish officers inspecting Soviet skiing manuals gained as loot from the [[Battle of Suomussalmi]]]]

Joseph Stalin was not pleased with the results of December 1939 in the Finnish campaign. The Red Army had been humiliated in defeats by smaller Finnish forces. By the third week of the war, Soviet propaganda was already working to explain the failures of the Soviet military to the populace: blaming bad terrain and harsh climate, and falsely claiming that the Mannerheim Line was stronger than the Maginot Line, and that the Americans had sent 1,000 of their best pilots to Finland. However, the Soviets were confronted with the unavoidable reality of the poor performance of their troops against the Finns. Stalin in particular was concerned about the effects of the war on Soviet reputation.<ref>[[#reiter|Reiter (2009)]], p. 126</ref> In late December, the Soviets decided to reduce their strategic objectives and focused on bringing the war to an end.<ref>[[#reiter|Reiter (2009)]], pp. 126, 127</ref>

Chief of Staff Boris Shaposhnikov was given full authority over operations in the Finnish theatre, and he ordered the suspension of frontal assaults in late December. Kliment Voroshilov was replaced with [[Semyon Timoshenko]] as the commander of the Soviet forces in the war on 7 January 1940.<ref name="Trotter_203-204">[[#Trotter2002|Trotter (2002)]], pp. 203–204</ref> The main focus of the Soviet attack was switched to the Karelian Isthmus. Timoshenko and Zhdanov reorganised and tightened control between different branches of service in the Red Army. They also changed tactical doctrines to meet the realities of the situation.<ref name="Laaks1999_424-425">[[#Laaksonen1999|Laaksonen (1999)]], pp. 424–425</ref>

The Soviet forces on the Karelian Isthmus were divided into two armies: the 7th and the 13th Army. The 7th Army, now under Kirill Meretskov, would concentrate 75 per cent of its strength against the {{convert|16|km|mi|abbr=on}} stretch of the Mannerheim Line between Taipale and the Munasuo swamp. Tactics would be basic: an armoured wedge for the initial breakthrough, followed by the main infantry and vehicle assault force. The Red Army would prepare by pinpointing the Finnish frontline fortifications. The 123rd Rifle Division then rehearsed the assault on life-size [[mockup|mock-ups]]. The Soviets shipped large numbers of new tanks and artillery pieces to the theatre. Troops were increased from ten divisions to 25–26 divisions with six or seven tank brigades and several independent tank platoons as support, totalling 600,000 soldiers.<ref name="Laaks1999_424-425"/> On 1 February, the Red Army began a large offensive, firing 300,000 shells into the Finnish line in the first 24&nbsp;hours of the [[bombardment]].<ref name="Trotter_214-215" />