On November 30, 1939, Red Army troops crossed the Soviet-­Finnish border, marking the start of a Soviet-­Finnish conflict that came to be known as the ‘Winter War’.

Despite the Soviet leadership’s expectations of a quick military campaign, the war with Finland became a protracted affair. the terrain of forests, marshes and lakes and the harsh winter conditions made fighting difficult. From the very start of the war, Western powers provided financial and military assistance to Finland. Foreign volunteers fought alongside Finnish troops. After suffering major losses, Red Army troops finally managed to break through the powerful fortifications on the Karelian Isthmus and reach Vyborg in late February 1940. Under these circumstances, Finland was forced to propose a peace treaty to the Soviet Union, despite the interest of the Anglo-French allies in continuing the Winter War.

The Peace Treaty between Finland and the USSR, signed on March 12, 1940, largely defined the contemporary border between the two countries. the security of Leningrad and the country’s north-­western border was assured.

The Winter War increased the hostility of Western ruling elites towards the Soviet Union, confirmed their doubts about the fighting capacity of the Red Army, and raised Hitler’s confidence in the possibility of a quick defeat of the USSR.

In April 1940, the Red Army high command met in the Kremlin to analyse the Winter War. It identified major shortcomings in the management, organisation and training of Soviet troops.