In November 1940, Crüger was appointed Gruppenkommandeur (group commander) of III. Gruppe (3rd group) of KG 30.[3] On 29 March 1941, Crüger and led his group in an attack against a British task force southwest of Crete. The group claimed three hits on the aircraft carrierHMS Formidable earning him a reference on 30 March 1941 in the Wehrmachtbericht (armed forces report), an information bulletin issued by the headquarters of the Wehrmacht.[5][6] Crüger married the German actress Carola Höhn on 13 September 1941 at the German consulate in Rome.[7] The marriage produced a posthumous son, Michael, who was born on 25 March 1942.[8]
After his wedding vacation Crüger took command as Geschwaderkommodore (wing commander) of the Schnellkampfgeschwader 210 on 30 September 1941 at the Eastern Front. He then became Geschwaderkommodore of Kampfgeschwader 77 on 13 March 1942. Fighting in the Mediterranean theater of operations Crüger went missing in action on 22 March 1942. Flying the Junkers Ju 88 A-4 3Z+AA (Werknummer 8627—factory number) he failed to return from a combat mission against the British forces on Malta.[9] Crüger and his crew, Oberfeldwebel Erich Atzler, Oberfeldwebel Kurt Raithel and Oberfeldwebel Walter Wagner, appear to have been shot down by Royal Navy AA fire while attacking shipping en route to Malta.[10][11]
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Fellgiebel, Walther-Peer[in German] (2000) [1986]. Die Träger des Ritterkreuzes des Eisernen Kreuzes 1939–1945 — Die Inhaber der höchsten Auszeichnung des Zweiten Weltkrieges aller Wehrmachtteile [The Bearers of the Knight's Cross of the Iron Cross 1939–1945 — The Owners of the Highest Award of the Second World War of all Wehrmacht Branches] (in German). Friedberg, Germany: Podzun-Pallas. ISBN978-3-7909-0284-6.
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Scherzer, Veit (2007). Die Ritterkreuzträger 1939–1945 Die Inhaber des Ritterkreuzes des Eisernen Kreuzes 1939 von Heer, Luftwaffe, Kriegsmarine, Waffen-SS, Volkssturm sowie mit Deutschland verbündeter Streitkräfte nach den Unterlagen des Bundesarchives [The Knight's Cross Bearers 1939–1945 The Holders of the Knight's Cross of the Iron Cross 1939 by Army, Air Force, Navy, Waffen-SS, Volkssturm and Allied Forces with Germany According to the Documents of the Federal Archives] (in German). Jena, Germany: Scherzers Militaer-Verlag. ISBN978-3-938845-17-2.
Schumann, Ralf (2007). Die Ritterkreuzträger 1939–1945 des LG 1 [The Knight's Cross Bearers 1939–1945 of LG 1] (in German). Zweibrücken, Germany: VDM Heinz Nickel. ISBN978-3-86619-013-9.
Shores, Christopher F.; Cull, Brian; Malizia, Nicola (1991). Malta: The Spitfire Year. London, UK: Grub Street. ISBN978-0-948817-16-8.