Born in Schrimm in the Province of Posen, Wilcke volunteered for military service in the Reichswehr of Nazi Germany in 1934.

After an assignment as fighter pilot instructor he volunteered for service with the Condor Legion during the Spanish Civil War in early 1939.

Wilcke then fought in the aerial battles of Operation Barbarossa, the German invasion of the Soviet Union.

Occasionally he still flew combat missions and on 23 March 1944, flying in defense of the Reich, he claimed his 162nd and last aerial victory and was killed in action by United States Army Air Forces long-range P-51 Mustang fighters near Schöppenstedt, in Lower Saxony.

Gruppe (3rd group) of Jagdgeschwader 53 (JG 53—53rd Fighter Wing),[Note 2] he had the Swastikas on his unit's aircraft painted over.

[2] As a Fähnrich (officer candidate), Wilcke was posted to the Kriegsschule (war school) in Dresden on 1 October 1934.

On 1 November 1935, he was transferred to the newly emerging Luftwaffe holding the rank of Oberfähnrich (senior officer candidate).

[6] World War II in Europe began on Friday, 1 September 1939, when German forces invaded Poland.

He claimed his first aerial victory on 7 November 1939, over the Western Front when he shot down an Armée de l'Air (French Air Force) Potez 630, a twin-engined fighter, near Völklingen during the Phoney War.

On 18 May 1940, he engaged in aerial combat with eight French Curtiss P-36 Hawk fighter aircraft and was shot down west of Rethel.

[Note 3] Harder had been last seen at 1:35 pm on 12 August and was reported as missing in action following combat east of the Isle of Wight.

The day of his appointment, Wilcke almost lost his life as well, when he was forced to bail out after engine failure over the English Channel.

[16] On 1 September 1940, on another bomber escort mission that started at 11:20 am, Wilcke claimed his fifth victory, a Hawker Hurricane, south of London.

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.

[26] He led another attack at 4:10 pm; while strafing airfields, he claimed his fifth aerial victory of the day, an "ace-in-a-day" achievement, taking his total to 18.

Gruppe had claimed 769 aerial victories for the loss of 6 pilots killed, 7 missing in action, 2 captured and 12 wounded.

[38] Wilcke claimed his 34th aerial victory on 11 December, during a fighter escort mission for Junkers Ju 88 bombers attacking Bir Hakeim.

To counter this threat, the Luftwaffe and the Regia Aeronautica (Italian Royal Air Force) conducted bombing raids to neutralize the RAF defenses and the ports.

Operating on the Eastern Front, Wilcke became a Geschwaderkommodore of JG 3 "Udet" on 11 August, replacing Oberst (Colonel) Günther Lützow, who was posted to the staff of the General der Jagdflieger (General of Fighters) as Inspector of the Day Fighters on the Eastern Front.

On 26 June 1942, JG  3 "Udet" was assembled at Schtschigry on the southern sector of the Eastern Front for the upcoming summer offensive, supporting the Wehrmacht's advance towards Stalingrad.

In the following months, JG  3 "Udet" was based at airfields at Gorshechnoye, Olkhovatka, Millerovo, Nowy-Cholan, Frolovo, Tuzov and Pitomnik.

[47] Two days later, he shot down six Yakovlev Yak-1 fighters over Stalingrad, his third "ace-in-day" feat, taking his total to 116 aerial victories.

It is possible that one of his opponents was Leytenant (Second Lieutenant) Nikolai Karnachyonok of 434 Istrebitel'nyy Aviatsionyy Polk (434 IAP—434th Fighter Aviation Regiment), who was killed in action that day and was posthumously made a Hero of the Soviet Union.

On 3 January 1943, this airfield had to be abandoned as well and the Geschwaderstab was relocated to Tazinskaya, there it remained until the fighting over the Stalingrad pocket ended.

[53] Although banned from flying,[Note 6] he was credited with two more victories on the Eastern Front, a Yak-1 on 28 December and an aircraft of unknown type on 5 January 1943.

[55] Wilcke was promoted to Oberst on 1 December 1943 and requested permission to fly operationally and lead his Geschwader from the air.

On this day, the USAAF was attacking aircraft factories at Braunschweig and other targets of opportunity in Münster, Osnabrück and Achmer.

The USAAF reported the loss of 29 bombers and 5 escort fighters while claiming 62 German aircraft shot down and another 2 destroyed on the ground.

[62] Wilcke had been nicknamed "Fürst" (prince) by his comrades on account of his attitude towards his men and paternal sense of responsibility.

[63] He had also been very conscious of his style and appearance and wore a very expensive and custom tailored leather coat, a trade which also added to his perception and fostered the nickname.