On July 3, Stalin ordered the Soviet army to implement a scorched-earth policy and either destroy or remove all useful supplies or facilities before retreating so that these resources would not fall into German hands. The Russians thus destroyed roads and bridges, burned fields of crops, and demolished or emptied many factories. Some major factories were even disassembled and moved eastward out of danger. The scorched-earth policy was effective and hindered the advancing German armies.
Although Britain and the United States were wary of Stalin and Russian Communism in general, the idea that the entire USSR might fall to the Germans was unacceptable. Within days of the invasion, Britain began providing Stalin with intelligence information gleaned directly from secret German transmissions that Allied code breakers had cracked and continued to read on a daily basis. In early July, the British also intensified their bombing of Berlin and other major German cities in an effort to force Hitler to recall some of the Luftwaffe forces back to Germany.
By late July, the first allied shipments of military supplies began reaching ports in the northern USSR. These shipments from Britain and the United States continued to grow significantly and included large numbers of aircraft and tanks, as well as food and medical supplies. From August 10–14, Churchill and Roosevelt met onboard a ship off Newfoundland and together laid out an extensive plan for providing large-scale assistance to the USSR.
By early September 1941, German forces had moved deep into European Russia, within easy reach of the major cities of Kiev and Leningrad. On September 10, Hitler decided to concentrate on the invasion of southern Russia and the Ukraine, hoping to gain access to the region’s economic resources, which included the wheat fields of the Ukraine, the citrus farms of the Black Sea coast, and the oil fields of the Caucasus.
On September 12, Hitler ordered the northern forces to cease their advance on Leningrad. Rather than enter the city, they were ordered to hold their current position, encircle the city, and slowly starve it to death. This strategy would allow several German tank divisions in the Leningrad area to be diverted for use in the south. Thus began the famous 900-day siege of Leningrad.
With more German troops available for in the south, the Ukraine collapsed quickly. After the Germans captured nearly half a million Soviet troops outside Kiev, the Ukrainian capital fell on September 19.