From early May to July 1942, Vatutin served briefly as deputy of the Chief of the General Staff of the Red Army until the German Army Group South embarked on its huge strategic offense, "Operation Blau". Initially, the German assault focused on Voronezh. They wanted to breach the Soviet front line at the Battle of Voronezh and then attack the Soviet Southern Front and Southwestern Front from the rear. On 1 July 1942, Stalin sent Vatutin as an all-powerful Stavka representative, to the critical Bryansk Front, which within a few days was renamed as Voronezh Front and placed under Vatutin's command.