Complex sentence: The Soviets had offensive operations of their own planned for the summer of 1943, one of which, Operation "Kutusov", was launched on 12 July against the German forces (Army Group Centre) in the Orel salient north of Kursk.
Split into simpler sentences: The Soviets had offensive operations of their own planned for the summer of 1943. On 12 July, Operation "Kutusov" was launched against Army Group Centre in the Orel salient, north of Kursk.