Klaus Mietusch was born on 5 August 1918 at Posen. After completing his flying training he was transferred to 2./JG 234, which was later redesignated 2./JG 26 on 1 September 1938. On 23 September 1939, Leutnant Mietusch was transferred to 7./JG 26. He participated in the Battle of France but, on 8 June 1940, was shot down in his Bf 109 E-1 (W.Nr. 2746) by a RAF Hurricane fighter near Neufchatel. He force-landed behind French lines unhurt, but was then shot in the buttocks by a French civilian . He became a prisoner of war of the French. He was released at the fall of France. Reunited with 7./JG 26, Mietusch gained his first victory on 31 May 1940, when he shot down a RAF Hurricane near Dunkirk. By the end of 1940, he had added a second victory and been promoted to Oberleutnant.
In January 1941, 7./JG 26, was relocated to Sicily. Mietusch gained three victories over Malta before 7./JG 26 were briefly deployed to participate in the assault on Yugoslavia. Mietusch gained a single victory over Yugoslavia on 6 April 1941, when he shot down a Fury biplane over Podgorica (in true it was Avia BH-33 flown by Narednik Djordje Cvetkovic). Redeployed over Malta, Mietusch added a further three victories, including a notable RAF ace. On 13 April, Mietusch attacked a Hurricane that had attacked four Bf 109s and shot it down for his eighth victory. The Hurricane was flown by Flying Officer E M “Imshi” Mason (15.4 confirmed and 3.6 damaged victories) of 274 Sqn, RAF who ditched his stricken aircraft in the sea having suffered wounds to his hand in the aerial combat and a broken nose in the ditching.
Mietusch also saw combat over North Africa gaining a single victory in the battles around Tobruk. By September, 7./JG 26 was relocated back to the Channel front. On 19 August 1942, he shot down two RAF Spitfire fighters over the Allied landings at Dieppe for his 20th and 21st victories. Hauptmann Mietusch led 7./JG 26 to Russia in February 1943 where it replaced I./JG 54 near Leningrad. Until June 1943, when 7./JG 26 was sent back to the Western Front, the Staffel shot down 63 Russian aircraft. Mietusch himself gained 15 victories during this period.
On 5 July 1943, Mietusch became Gruppenkommandeur of III./JG 26. His 50th victory was a B-17 shot down over Cambra on 20 October. On 8 March 1944, Mietusch claimed a B-17 as his 60th victory. However, when attempting to attack the withdrawing bombers, Mietusch was shot down in Bf 109 G-6 (W.Nr. 162 032) “Black 21” near Meppen by the USAAF P-47 fighter escort. He baled out and landed safely but had suffered injuries destined to keep him in hospital for the next few weeks. He was awarded the Ritterkreuz for his 60th victory on 26 March 1944.
He received promotion to the rank of Major in April. While landing at Rouvres-Étain on 12 April, Mietusch’s Bf 109 G-6 (W.Nr. 162 345) “Black 24” hit a bomb crater and overturned. He suffered injuries that put him back in hospital for three weeks. Mietusch shot down a USAAF P-38 twin-engine fighter near Chartres on 4 July to record his 70th victory.
Mietusch was engaged in combat with USAAF P-51 fighters on 17 September 1944. After gaining his 75th, and final victory, he was shot down and killed in Bf 109 G-6 (W.Nr. 441 646) “Black 25” in the vicinity of Rath-Aldekerk by the American ace, Lieutenant William Beyer (9 victories) of the 376th Fighter Squadron of the 361st Fighter Group, USAAF.
He was posthumously awarded the Eichenlaub (Nr 653) on 18 November. In 452 combat missions Klaus Mietusch gained 75 victories. He was wounded several times and was shot down ten times.