As the Germans advanced through Russia during Operation Barbarossa, they extended
their lines from Leningrad in the North to Stalingrad in the south, and Stalingrad
had to be taken in order to secure the Caucasus and create a route to the
Middle East. But the Soviets held the German advance at Stalingrad on the
Volga River and were determined that the Nazis would advance no further. The
Battle of Stalingrad saw bitter, bitter, fighting, much of it house-to-house
and hand-to-hand. Winter set in, and the Germans were woefully unprepared.
They did not have winter clothing and were unaccustomed to fighting in such
weather.
indicates an external link 
