 The strength of the Red Army north of Lake Ladoga ( in Ladoga Karelia ) surprised the Finnish General Staff . Two Finnish divisions were deployed there : the 12th Division led by Lauri Tiainen and the 13th Division led by Hannu Hannuksela . They also had a support group of three brigades , bringing their total strength to over 30 @,@ 000 . The Soviets deployed a division for almost every road leading west to the Finnish border . The Eighth Army was led by Ivan Khabarov , who was replaced by Grigori Shtern on 13 December . The Soviets ' mission was to destroy the Finnish troops in the area of Ladoga Karelia and advance into the area between Sortavala and Joensuu within 10 days . The Soviets had a 3 : 1 advantage in manpower and a 5 : 1 advantage in artillery , as well as air supremacy . 
