On 1 August 1943, Sturm was appointed acting "Staffelkapitän" (squadron leader) of 4. "Staffel" (4th squadron) of JG 52. He replaced "Leutnant" Helmut Lipfert in this capacity who was transferred to the 6. "Staffel" (4th squadron) of JG 52. Sturm later officially became the "Staffelkapitän" of 4. "Staffel" on 1 September, succeeding "Hauptmann" Gerhard Barkhorn who was given command of II. "Gruppe". That day, the "Gruppe" moved to an airfield at Karlivka where they fought in the aftermath of the Belgorod–Kharkov offensive operation, also referred to as the fourth Battle of Kharkov. Here, Sturm claimed his first aerial victory as "Staffelkapitän" when he shot down a La-5 fighter. In November, the Red Army launched the Kerch–Eltigen operation leading to the Crimean offensive in early 1944. On 2 November, II. "Gruppe" was moved to Baherove where elements of the "Gruppe" remained until 19 March 1944. On 5 November, Sturm again became an "ace-in-a-day" when he shot down an Il-2 ground attack aircraft and five Yakovlev Yak-1 fighters over the Soviet bridge heads. The following day, he claimed six further victories, five Yak-1 fighters and a Bell P-39 Airacobra, making him yet again an "ace-in-a-day".