War against the Soviet Union

On 8 June 1941, the bulk of JG 53's air elements moved via Jever, in northern Germany, to Mannheim-Sandhofen. There the aircraft were given a maintenance overhaul prior to moving east.^[5] On 12 June, III. Gruppe was ordered to transfer to a forward airfield at Sobolewo. On 21 June, the Geschwaderkommodore (wing commander) of JG 53 and its Gruppenkommandeure were summoned to nearby Suwałki, where Generalfeldmarschall (field marshal) Albert Kesselring gave the final instructions for the upcoming attack. Hauptmann Wolf-Dietrich Wilcke, the Gruppenkommandeur of III. Gruppe, briefed his pilots that evening.^[6]

On 22 June, the Geschwader crossed into Soviet airspace in support of Operation Barbarossa, the invasion of the Soviet Union, which opened the Eastern Front. III. Gruppe took off on its first mission at 3:20 am with the Gruppenstab (headquarters unit) and 7. Staffel targeting Soviet airfields at Alytus and Oranji.^[7] Thad day, Harder claimed his first aerial victory, shooting down an I-17 fighter, an early war designation for the Mikoyan-Gurevich MiG-1.^[8]

On 25 September, Harder got disoriented and his Bf 109 F-2 (Werknummer 9212) ran out of fuel resulting in an emergency landing near Novgorod.^[9] In early October, III. Gruppe was withdrawn from the Eastern Front, relocating to Mannheim-Sandhofen. The air elements left on 4 October with the ground elements travelling by train, arriving in Mannheim-Sandhofen on 13 October.^[10]

Mediterranean theater

At Mannheim-Sandhofen, III. Gruppe was equipped with the then new Bf 109 F-4. On 8 November, the Gruppe moved to Husum in northern Germany where they stayed until 14 November.^[11] They were then ordered to relocate to the Mediterranean theater in Sicily. The ground elements arrived at Catania Airfield on 28 November followed by the air elements two days later.^[12] On 13 October, Harder claimed a Curtiss P-40 Warhawk fighter on a morning escort mission for Junkers Ju 87 dive bombers. Later that day, he claimed a second P-40 shot down.^[13]

On 12 January 1943, Harder was awarded the German Cross in Gold (Deutsches Kreuz in Gold) and promoted to Oberleutnant (first lieutenant) on 1 February.^[3] On 3 February, Harder received news that his wife had given birth on 30 January to their daughter Elke.^[14] Two days later, Harder was appointed Staffelkapitän (squadron leader) of 7. Staffel of JG 53. He replaced Hauptmann Wilfried Pufahl who was transferred. From 25 May onwards, Harder only led the Staffel from the ground while in the air they were initially led by Leutnant Franz Barten and from July by Leutnant Walter Hicke.^[15] Harder had been taken off combat duty following the death of his younger brother Rolf in April.^[3]

On 22 March, Harder claimed his first heavy bomber when he shot down a Boeing B-17 Flying Fortress bomber from a force of 24 B-17s, escorted by 40 fighter aircraft, on mission heading for Palermo.^[16] On 8 May, 8. Staffel flew from Sciacca on escort mission for three military transports heading for Tunesia without engaging in combat. Later that day east of Cape Bon, Harder claimed two Spitfire fighters shot down.^[17] Together with Franz Schieß, Harder was promoted to the rank of Hauptmann (captain) on 1 September 1943.^[18]

Group commander

On 22 January 1944, Allied forces launched the amphibious landing Operation Shingle, also known as the Battle of Anzio. In an attempt to contain the Allied beachhead at Anzio and Nettuno, German forces moved available forces into the combat area. In consequence, III. Gruppe relocated to Orvieto near Lake Bolsena on 24 January.^[19] In this combat area on 7 February, Harder claimed his 40th in total and first aerial aerial victory after he was again allowed to fly operationally over a Spitfire near Lake Albano. On 12 February, III. Gruppe moved to a makeshift airfield at Arlena di Castro located southeast of Lake Bolsena.^[20] Escorting German ground attack aircraft on 14 February, Harder shot down a Lockheed P-38 Lightning.^[21] The following day, Harder was informed that he had been appointed Gruppenkommandeur of I. Gruppe of JG 53, replacing Major Friedrich-Karl Müller who was transferred. Prior to taking his new command, Harder met with Oberst Günther Freiherr von Maltzahn, the Jagdfliegerführer Oberitalien (Fighter Leader Northern Italy), in Udine where he received more specific orders. Command of his 7. Staffel then went to Oberleutnant Rolf Klippen.^[22] At the time, I. Gruppe was based at Maniago.^[23]

The United States Army Air Forces (USAAF) Fifteenth Air Force attacked Regensburg on 25 February. I. Gruppe intercepted the bombers north of Laibach, present-day Ljubljana. In the resulting aerial combat fought between 11:25 and 12:05, Harder shot down one of the Consolidated B-24 Liberator bombers near Klagenfurt. However, his wingman Oberleutnant Horst Torrau was shot down and is missing in action since.^[24] In early March, a soldier of 2. Staffel, a squadron of Harder's I. Gruppe, was killed in a fight with residents of Maniago. In an act of retaliation, a flight of 2. Staffel made multiple strafing attacks on Maniago during a training exercise. Whether Harder was aware of the plans prior to the attack remains unknown. Harder however was summoned by the Geschwaderkommodore Oberstleutnant Helmut Bennemann to report on the incident.^[25]

On 25 April, Harder attacked a four-engined bomber formation and shot one of them down and rammed another after his aircraft was damaged thereby claiming his aerial victories number 49 and 50.^[26][27] Elements of JG 53 had been scrambled at 11:00 and intercepted a flight of approximately 30 B-24s at 11:30 west of Forlì. Harder shot down one of the B-24s and rammed a second. He bailed out of his Bf 109G-6 (Werknummer 162717) near Casentino, spraining his ankle and breaking his wrist.^[28] On 1 May, Harder was promoted to Major (major).^[29]

On 4 January 1945, Harder claimed his 64th and last aerial victory when he shot down a Lavochkin La-5 fighter. Shortly after, he was ordered to Berlin where he met with Reichsmarschall Hermann Göring. The purpose of the meeting was to present Harder with the Knight's Cross of the Iron Cross with Oak Leaves (Ritterkreuz des Eisernen Kreuzes mit Eichenlaub). However, expressed his concerns about the technical superiority of the Allied aircraft to Göring. This infuriated Göring to the point that Harder was yelled at and accused of incompetence. Harder was then released and sent back to his unit where he arrived on 16 January without the Oak Leaves.^[30] On 21 January, Harder was again ordered to Berlin to take command Jagdgeschwader 11 (JG 11—11th Fighter Wing). The next day, Harder left I. Gruppe of JG 53. Command of the Gruppe was temporarily given to Hauptmann Wolfgang Ernst, then to Hauptmann Erich Hartmann, before Hauptmann Helmut Lipfert officially took command on 15 February.^[31]

Wing commander and death

In late January 1945, Harder took command of JG 11 as appointed Geschwaderkommodore. He replaced Major Günther Specht who had been killed in action on 1 January during Operation Bodenplatte.^[32] On 12 January, Soviet forces launched the Vistula–Oder offensive on the Eastern Front. In consequence on 21 January, JG 11 moved to Strausberg, located 30 kilometers (19 miles) east of Berlin, where they arrived on 23 January.^[33] For his 64th aerial victory, Harder was then awarded the Oak Leaves to his Knight's Cross on 1 February 1945. He was the 727th member of the German armed forces to be so honored.^[29] In early February, JG 11 predominately flew ground support missions in the area of Kienitz, present-day part of Letschin, where Soviet forces had created the first bridgehead across the Oder.^[34]

On 17 February, Harder and his wingman Leutnant Hans Jung flew an aerial reconnaissance mission over the Oder. During the landing approach at Werneuchen, Jung observed Harder's Bf 109 G-14/AS (Werknummer 784738) going into an unexplainable steep dive, crashing into the ground and killing Harder. Technical experts later analyzed the wreckage and came to the conclusion that engine failure had caused the accident. The piston of cylinder 12 had penetrated the engine block, escaping toxic fumes thus intoxicated Harder who then lost control of the aircraft.^[35] Command of JG 11 was then given to Major Anton Hackl who took command on 22 February.^[36]

Aerial victory claims

According to US historian David T. Zabecki, Harder was credited with 64 aerial victories.^[37]Obermaier also lists him with 64 aerial victories, 17 over the Eastern Front and 47 in the Mediterranean theater and Western Allies, including nine four-engined heavy bombers.^[1] Mathews and Foreman, authors of Luftwaffe Aces – Biographies and Victory Claims, researched the German Federal Archives and state that he was credited with more than 56 aerial victories, plus one further unconfirmed claim. This figure includes at least 12 aerial victories on the Eastern Front and 44 over the Western Allies, including ten four-engined heavy bombers.^[38]

Victory claims were logged to a map-reference (PQ = Planquadrat), for example "PQ 14 Ost N/LH-4". The Luftwaffe grid map (Jägermeldenetz) covered all of Europe, western Russia and North Africa and was composed of rectangles measuring 15 minutes of latitude by 30 minutes of longitude, an area of about 360 square miles (930 km²). These sectors were then subdivided into 36 smaller units to give a location area 3 km × 4 km (1.9 mi × 2.5 mi) in size.^[39]

Awards

• Honor Goblet of the Luftwaffe on 16 November 1942 as Leutnant and pilot^[61]
• German Cross in Gold (12 January 1943)^{[62][63][Note 17]}
• Knight's Cross of the Iron Cross with Oak Leaves
  • Knight's Cross on 5 December 1943 as Hauptmann and Staffelkapitän in the III./Jagdgeschwader 53^{[64][Note 18]}
  • 727th Oak Leaves on 1 February 1945 as Major and Geschwaderkommodore of the Jagdgeschwader 11^[62][65]