Why was the  Battle of Stalingrad so important?

Battle of Stalingrad was critical and device fight between Nazi Germany and Soviet Union for few reasons. Firstly, it was deadliest and most intense fighting between two powers, binding very sizeable forces. The city itself was strategic as it hold the keys to the southern part and oil fields. Thirdly, it had a symbolic value for Stalin. And last but not least, it turned the tide in the war.