Question

One reason the battle at Stalingrad was a turning point in the war was that it forced Germany to fight a defensive, rather than an offensive war.

Answer 1

This is true. The Germans lost an entire army group (the Sixth Army was annihilated at Stalingrad) and the Wehrmacht lost a great number of men and war materiel that crippled their offensive capabilities. They tried to regain the initiative at the Battle of Kursk later in '43 but lost that as well.