He claimed his first aerial victory on 12 March 1943 when he downed a Royal Air Force (RAF) Supermarine Spitfire fighter near Fécamp.

[6] In late January 1944 following the Allied amphibious landing in Italy known as Operation Shingle, I. Gruppe under the command of Hauptmann Erich Hohagen was moved to Aix-en-Provence Aerodrome in southern France.

[7] On 9 February, Lemke engaged Spitfires from the 52nd Fighter Wing which were attacking shipping off the coast of France.

[8] In this engagement, Lemke also shot down Flight Officer James H. Montgomery and Lieutenant John L. Bishop, both pilots killed in action.

The USAAF sent 200 Boeing B-17 Flying Fortress and 80 Consolidated B-24 Liberator bombers to the Rome marshalling yards on 3 March.

[3] By the early summer of 1944, Lemke's squadron was again moved, this time to Creil, an airfield north of Paris.

Gruppe of JG 2, replacing Hauptmann Josef Wurmheller who had been killed in action on 22 June.

[4] The Gruppe flew its last combat mission from Creil, France on 19 August before they relocated to Königsberg in der Neumark, present-day Chojna, Poland, for a period of rest and replenishment.

The Gruppe moved to Mohrin, present-day Moryń, on 5 October where training of the newly assigned pilots continued.

It is said that Lemke led his surviving men north, though no record exists of the Gruppe movements.

[18] In the final days of the war, Lemke was nominated for the Knight's Cross of the Iron Cross with Oak Leaves (Ritterkreuz des Eisernen Kreuzes mit Eichenlaub) which were not awarded before the war ended.