Spanish Civil War Oesau started his operational career with the Condor Legion, along with future contemporary aces such as
Werner Mölders and
Adolf Galland. He was one of the first to join 3.
Jagdgruppe 88 in Spain in April 1938. The
Staffel, commanded by
Werner Mölders, took part in the
Spanish Civil War where Oesau claimed nine victories, flying 130 combat missions. For this he received the
Spanish Cross (
Spanienkreuz) in Gold with Diamonds. He was also wounded in this conflict which earned him the Spanish Wound Badge. He also received the
Medalla de la Campaña and the
Medalla Militar.
Western Front 1939–40 On 1 March 1939 Oesau joined the Headquarters Flight (
Stabsschwarm) of I./JG 2. By 15 July 1939 Oesau was promoted to
Oberleutnant and given command of 2./JG 20. On 15 July 1939, I./JG 20 was activated in
Döberitz initially consisting of two
Staffeln drawn from JG 2. Prior to the invasion of Poland I./JG 20 was transferred to
Strausberg on 26 August 1939. From there, the group was transferred to Sprottau (modern
Szprotawa) anticipating an attack from the Polish Air Force. A week later the group moved to
Brandenburg. On 21 February 1940, the unit was relocated to
Bönninghardt under the control of
JG 51. It continued to operate in this fashion until the end of the Battle of France. On 4 July it was re–designated III./JG 51. Oesau served as
Staffelkapitän of 7./JG 51.
Battle of France Oesau got his first World War II victory during the Battle of France on 13 May 1940, when he claimed a French Curtiss
P-36 Hawk over
Halsteren in the Netherlands, earning him the Iron Cross 1st class (). On 31 May, he claimed three Spitfires during a patrol North West of
Dunkirk and next day he claimed a
Bristol Blenheim. On 13 June 1940, he shot down the last French aircraft kill claimed by JG 51, a French
Amiot bomber. By the end of hostilities in France on 25 June, his World War II tally stood at 5 (13 including Spanish kills). Following the Battle of France, the Luftwaffe started its attacks on Channel convoys as a prelude to the Battle of Britain. The primary task of JG 51 during this time was to provide fighter escort to these bomber missions. The commander of JG 51,
Oberst Theo Osterkamp established a policy of unrestricted
combat air patrol (
freie Jagd) of fighter
Staffeln providing loose protection rather than close escort to the bombers, actively seeking out
Royal Air Force fighters. On 7 July 1940 Oesau claimed one Spitfire.
Battle of Britain On 10 July 1940, the first major clashes of the Battle of Britain occurred in a phase known as the
Kanalkampf. 20 Bf 109s of III./JG 51 led by
Hauptmann Hannes Trautloft and 30
Messerschmitt Bf 110 C of I./
Zerstörergeschwader 26 escorted 20
Dornier Do 17 bombers of II./
Kampfgeschwader 2 attacking a large convoy off
Folkestone.
Oberleutnant Oesau was leading 7./JG 51. Trautloft noticed three of a flight of six intercepting
Hurricanes of
No. 32 squadron higher than the escorts, attempting to intercept the bombers. Soon they were joined by four squadrons of British fighters:
No. 56 Squadron,
No. 111 Squadron,
No. 64 Squadron and
No. 74 Squadron. Oesau was able to claim three Spitfires. Two 7./JG 51 aircraft crash landed in France. British losses show that no Spitfire was lost or destroyed in the ensuing battle. Only one No. 32 Hurricane, piloted by
Pilot Officer Higgs, was destroyed in a collision with one of the Do 17s and only one other Hurricane was damaged. It is possible Oesau was responsible for damaging Higgs' Hurricane, causing him to lose control. Two Spitfires landed with light damage while a third was also slightly damaged and force-landed at
RAF Manston. Over claiming of enemy losses was rife on both sides during the battle. On 19 July, III./JG 51 were confronted by
Defiants of No. 141 Squadron south of
Folkestone. As the German pilots were now aware of the Defiant's lack of forward armament, they soon gained the advantage in combat and claimed 11 Defiants shot down in 8 minutes. Oesau was credited with one Defiant, taking his score to 19. He was the first one of JG 51 to reach double digits in World War II. RAF losses record six Defiants destroyed and two damaged. On
18 August 1940, III./JG 51 escorted Dorniers attacking
Hornchurch airfield. Intercepted by Hurricanes over Kent, Oesau claimed one Hurricane shot down as his 20th victory, earning him the
Knight's Cross of the Iron Cross () two days later, the first pilot of JG 51 to be thus honored. On 24 August 1940, Trautloft took over as
Geschwaderkommodore of
Jagdgeschwader 54, and Oesau replaced him as
Gruppenkommandeur of III./JG 51 while command of 7./JG 51 went to
Oberleutnant Hermann Staiger. By October 1940, Oesau had a total score of 48 (including 26 Spitfires). On 10 November 1940, Oesau succeeded
Wilhelm Balthasar as
Gruppenkommandeur of III.
Gruppe of
Jagdgeschwader 3. In consequence, command of III.
Gruppe JG 51 was handed to
Hauptmann Richard Leppla. With 39 victories he was currently the 4th highest scoring fighter pilot behind
Helmut Wick,
Werner Mölders and
Adolf Galland. On 5 February 1941, the RAF flew
"Circus" No. 3 targeting the airfield at
Saint-Omer. That day, Oesau shot down the Hurricane piloted by Sergeant H. D. Denchfield from
No. 610 Squadron over
Desvres, France. This was his 40th aerial victory. Oesau was awarded the
Knight's Cross of the Iron Cross with Oak Leaves () next day. It also earned him a second entry in the
Wehrmachtbericht. In early 1941, JG 3 returned to Germany to replace their
Messerschmitt Bf 109 'Emils' with the new 'F' variant (
Friedrich). However, Oesau disliked the Bf 109 F and kept flying his 'Emils' for some time. JG 3 returned to France in May 1941 and Oesau added two more kills on 16 May and 28 May bringing his total to 51.
Operation Barbarossa The
Gruppe relocated to an airfield at
Moderówka on 18 June where the
Gruppe concluded their last preparations for
Operation Barbarossa, the German invasion of the Soviet Union on 22 June 1941. At the start of the campaign, JG 3 was subordinated to the
V. Fliegerkorps (5th Air Corps), under command of
General der Flieger Robert Ritter von Greim, which was part of
Luftflotte 4 (4th Air Fleet), under command of
Generaloberst Alexander Löhr. These air elements supported
Generalfeldmarschall Gerd von Rundstedt's
Heeresgruppe Süd (Army Group South), with the objective of capturing Ukraine and its capital
Kiev. Oesau shot down his first Soviet aircraft on 24 June, and by 30 June 1941 had reached his 60th victory, downing a
Tupolev SB bomber. Next day he downed three more SB bombers near Lvov (modern
Lviv,
Ukraine). This earned him his 3rd entry in the Wehrmachtbericht. On 10 July 1941, Oesau claimed 5 more aircraft and two more kills by 11 July 1941. On 12 July 1941, he shot down 7 Soviet aircraft in one sortie. In the five weeks since moving to the Eastern Front, Oesau was credited with 44 Soviet aircraft downed. He became the third pilot to reach 80 victories, the 80th kill an
Ilyushin DB-3 bomber. He was awarded the
Knight's Cross of the Iron Cross with Oak Leaves and Swords () on same day. He was the third person to earn the Swords. He was again then wounded, receiving heavy splinter injuries in face and knee. A fortnight later he was transferred to the Western Front to take over JG 2.
Defence of the Reich 1941–44 He succeeded Balthasar for the second time as JG 2 commander, who had died in combat with Spitfires over northern France when he pulled the tail off his Bf 109 F in a dive. The Bf 109 F-2 proved an excellent match to the Spitfire V, but Oesau disliked its reduced armament compared to the 'Emil', and continued to fly an E-4 model in preference to the Bf 109 F, until lack of spares forced him to switch to the newer variant. Upon his appointment on 4 July 1941, he addressed JG 2 with the following words. . JG 2 was tasked with defending targets in occupied France against the RAF fighter offensive. For the next two years Oesau led JG 2 through the war of attrition waged by the RAF. On 10 August 1941 Oesau claimed a Spitfire for his first kill with JG 2. Over the next two days, he claimed four more Spitfires. By the end of September 1941, Oesau had claimed two more Spitfires. JG 2 participated in the Luftwaffe air cover of the
Channel Dash. Two
Boeing B-17C Flying Fortresses of
No. 90 Squadron attacked the German battleships and . In one of the highest altitude interceptions of World War II, the bombers were attacked by I./JG 2, resulting in the destruction of one. This aircraft put JG 2's score past the 800 mark, matching the score of their Great War namesake. Kills No. 88 to 92 were all Spitfires claimed between Calais and Dungeness on 12 August 1941. Oesau claimed his 100th kill on 26 October 1941, the third pilot to do so. This earned him his 4th entry in the
Wehrmachtbericht. He was then grounded from flying on operations, as his experience and leadership qualities were regarded as too valuable to risk further in front line combat. He did fly on occasional sorties, the most famous involving the shooting down of an
Avro Lancaster bomber of
No. 44 Squadron RAF piloted by Warrant Officer G. T. Rhodes in April 1942, during a rare
RAF daylight raid on the MAN engine plant in Augsburg. It was his 101st kill. In August 1942, the
Geschwaderstab of JG 2 exchanged their Bf 109 F aircraft for
Fw 190 A–2s. From late 1942 onwards JG 2 was in the front line against the increasingly numerous
United States Army Air Forces (USAAF) day bomber formations of B-17s and B-24s. Oesau added four more to his tally by mid-1943. Shortly before his 30th birthday, Oesau was elevated to a series of Luftwaffe staff and administration positions. On 1 July 1943 he was posted as Fighter Leader Brittany (
Jagdfliegerführer
Bretagne), before being appointed as
Geschwaderkommodore of JG 1 on 12 November 1943, following the death of JG 1's
Hans Philipp in October 1943. The ban on Oesau's combat flying was lifted. While commanding JG 1, Oesau became an expert (
Experten) at shooting down 4 engine bombers, with 14 bomber kills claimed. He was awarded the
Combined Pilots-Observation Badge in gold and diamonds on 17 October 1943. He was awarded the
German Cross in Gold () on 10 January 1944. For Commander-in-Chief of the Luftwaffe
Hermann Göring it was an ongoing concern that inadequate numbers of fighters were able to continually engage the bomber streams, at the very time that the
USAAF's 8th Air Force's new commander, Maj. Gen.
Jimmy Doolittle had instituted a
new fighter strategy against the Luftwaffe. Hence on 23 February 1944 – near the midpoint of the USAAF's
Big Week bomber offensive against the Luftwaffe, also being carried out by the
15th Air Force flying out of Italian bases –
Generalmajor Joseph Schmid Commander of
I. Jagdkorps established a new rule for the fighters returning to base. They were to arrive at the nearest designated fighter airfield for resupply instead of returning to their own base. They were to be commanded by the senior pilot landing on that airfield, irrespective of their unit. This was meant to turn around the fighters in time to intercept returning bombers. On the next day, B-24s of
2nd Bomb division of the
Eighth Air Force bombed
Gotha. JG 1 (under Oesau), JG 11 and JG 3 were sent to intercept. Due to high winds, the bombers were ahead of the escorts unprotected. Two groups of JG 1 met them before Gotha and 9 B-24s were claimed as a result. Since B-17s of
1st Bomb division also bombed
Schweinfurt, other fighter units also arrived to intercept, eventually involving almost all the Western day fighter units of the Luftwaffe. This caused some confusion among pilots landing on airfields other than their own. This tested the directive of Schmid. Oesau led one of two such improvised formations successfully, with the other led by Hauptmann Borris of I./JG 26 Oesau added 4 fighters to his score between January and March 1944, and his tally stood at 117. On 8 May 1944 he claimed a
Thunderbolt shot down over Hanover; his last kill. ==Death==