The group took part in the Invasion of Poland, later moving to the Western Front as the redesignated III Gruppe, Jagdgeschwader 51.

[Note 1][1][2] Oesau started his operational career with the Condor Legion, along with future contemporary aces such as Werner Mölders and Adolf Galland.

[Note 2] The Staffel, commanded by Werner Mölders, took part in the Spanish Civil War where Oesau claimed nine victories, flying 130 combat missions.

[3][4] 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 (Eisernes Kreuz 1.

By the end of hostilities in France on 25 June, his World War II tally stood at 5 (13 including Spanish kills).

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 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.

With 39 victories he was currently the 4th highest scoring fighter pilot behind Helmut Wick, Werner Mölders and Adolf Galland.

These air elements supported Generalfeldmarschall Gerd von Rundstedt's Heeresgruppe Süd (Army Group South), with the objective of capturing Ukraine and its capital Kiev.

[1][2][15][21] 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 109F in a dive.

[1][22][23][24] In the spirit of Manfred von Richthofen, and following the example set by my predecessors, Major Wick and Hauptmann Balthasar, constant readiness and devotion to duty will enable us to achieve yet further successes.

[1][26][27] 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.

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.

[1][2] While being the Geschwaderkommodore of JG 1 Oesau frequently received his share of Hermann Göring's anger and frustration over the failure to beat off the Allied bomber offensive.

In this context it should be stated that in order not to risk one of the Luftwaffe expert's life [German fighter aces were called Experten], there was an automatic ban on Oesau for further combat flying since his 100th victory.

On 11 May 1944 one thousand U.S. heavy bombers from Eighth Air Force attacked railway targets in Eastern France and North East Belgium.

"[4] Angered by this comment, Oesau took off in a Messerschmitt Bf 109 G-6/AS "Green 13" (Werknummer 20601—factory number) from Paderborn despite a high fever.

While attempting an emergency landing, his Gustav received a final burst of fire in the cockpit area and crashed into the ground 10 kilometres (6.2 miles) southwest of St. Vith.

Doyle noted bullet damage in the cockpit area and his gun camera footage showed that it was Oesau's Green 13.

German records indicated that his death was caused by an explosive shell in the cockpit, his body having several bullet wounds.

Later an image from the Gun camera was published (without caption) that purportedly showed Oesau's aircraft from the right side.

Walter Oesau is buried in Meldorf, close to his birthplace and the town museum (Dithmarscher Landesmuseum) has documented his last journey in pictures.

However, being a star and staying in Göring's favor required keeping up the kill rate and promotions were invariably linked to scores.

According to Dr. Kurt Tank, the Focke–Wulf designer, although many of the younger generation were good flyers, they were unable to cope with problems of overall planning and broader strategic aspects.

However, Oesau was one of the outstanding leaders ever produced by Luftwaffe fighter wings with the likes of Werner Mölders and Adolf Galland.

This, coupled with the acute shortage of well trained pilots and the fact that by 1943 they were facing a better equipped and well-trained enemy, meant the life expectancy of even the most gifted was tragically short.

Author John Weal says that, although other Geschwaderkommodore would end up dying in combat, nothing would showcase the changing fortunes of Luftwaffe fighter forces than the death of Walter Oesau.

While Oesau commanded, JG 2, like many others, dropped the special symbols for Stab (headquarters flight) units in favor of numerals.

The authenticity of the photograph is questioned by some as there are also Ju 87 photos supposedly signed by Oesau (he never flew a Stuka bomber).