 "Gruppe" flew missions in the vicinity of Belgorod and Prokhorovka, over the front lines of the 6th Army.That day, Gratz claimed his first two aerial victories, a Mikoyan-Gurevich MiG-3 fighter which at the time was referred to as an I-61, and an Ilyushin Il-2 ground-attack aircraft.On 12 May, German forces launched Operation Fredericus, also referred to as the Second Battle of Kharkov, with the objective to eliminate the Izium bridgehead over Seversky Donets.