In June, German fascists launched a surprise attack on the Soviet Union. The army led by German field marshal von Lieber is approaching Leningrad (St. Petersburg) at the gates. Leningrad was besieged and almost completely cut off from the outside world. Land traffic was completely interrupted, and the air passage could only play a liaison role, because the air control was not in the Soviet Union at that time. The only thing that can connect with the rear is Lake Ladoga, but the transport ships on the lake are often sunk by German planes, and the food supply in the city is becoming more and more difficult. Fortunately, shortly after the arrival of winter, the coast of Lake Ladoga began to freeze, and the thickness of the ice layer quickly exceeded 10 cm. Soviet troops defended the south bank of Lake Radogar and protected this life passage. The bus carrying goods finally caught up with this winter route.