The article studies changes in the life of Leningrad caused by the war with Finland. As an important industrial and administrative center, as well as a key transport node, Leningrad had to adapt to military life. Preparations for war, such as partial mobilization, evacuation hospitals deployment, local air defense reinforcement, continued throughout the fall of 1939. The Soviet troops took the offensive on November 30, 1939. Soon Leningrad had to adapt its economy to military demands. Firstly, there was a need to produce various equipment (from warm clothes to ski) to help to conduct war operations in specific winter conditions. Secondly, the production of weapons and ammunitions were to be increased, and new models of military equipment were proposed and created. The campaign for the accelerated growth of production could not probably avoid the emergence of some bizarre projects. A good example of such projects was a «snow torpedo» of the engineer Makarov. It was supposed to be able to move using jet engines. Such a serious attitude to awkward projects may illustrate agiotage caused by the rapid restructuring of the city industry for the war needs. Leningrad was a crucial railway node for frontline supply. At the same time, a railway system was not prepared for such substantial traffic increase. Since the first day of the war, train locks and blocks began to happen. Railway traffic increased in the region during the war while decreased in general in the whole Soviet Union. At the same time, the intensification of military traffic was accompanied by the decrease of Leningrad civil traffic. The city experienced an acute supply crisis. Most of the difficulties were related to the delivery of fuel (coal, peat, wood), and the work of a number of enterprises was interrupted because of that. During the Soviet-Finnish war, Leningrad was a large military medical center. The war caught the Soviet military medicine by surprise too, because nobody could have predicted such a huge number of injured. Measures to mobilize resources - human (including professionals: doctors, drivers), cars, school buildings continued during all the three and a half months of the war. As a result of the transformation of Leningrad to a frontline city, its industry, transport, supply, medicine, and education suffered numerous changes. The difficulties that have occurred were much more severe than expected. The war affected the lives of all Leningrad residents and served as a lesson for many of them.
Key words: Soviet-Finnish war, Leningrad, everyday life, military mobilization measures, industry, transport, hospitals.