Wilhelm "Willi" Steinmann joined the Luftwaffe in 1936 and trained as a bomber pilot serving with 3./KG 53 from 1939 to 1941, and later as Technischer Offizier with II./Fliegerkorps. He then underwent conversion training to become a fighter pilot.

On 6 October 1942, Steinmann was posted to I./JG 27's Gruppenstab based on the Channel Front. He then flew with 3./JG 27 where he claimed his first victory on 18 May 1943, a RAF Typhoon down over the Channel, and his second, a Spitfire, on 1 June. However, it was in fact the Bf 109 G-6 flown by his Gruppenkommandeur Hptm. Erich Hohagen who was wounded and forced to bail out of his crippled machine.

Due to this debacle Steinmann was promptly transferred to the backwater command of the Jagdfliegerführer Rumänien. Here Hptm. Steinmann was soon deployed as the Staffelkapitän of 1./JG 4. His next combat success came on 1 August 1943 when he claimed two B-24 Liberators during "Operation Tidal Wave", the USAAF's low-level raid on the Ploesti oil refineries. Steinmann was injured by bombers' return fire and was hospitalized for six weeks before returning to duty on 14 September.

On this date "Willi" was appointed Staffelkapitän of 1./JG 4 now based in Italy, and on 23 January 1944 appointed Gruppenkommandeur I./JG 4. He claimed 15 victories, mainly fighters, while flying in the Mediterranean theatre. Steinmann relinquished command of I./JG 4 to Hauptmann Walter Hoeckner on 14 February 1944. He was re-appointed Gruppenkommandeur on 26 August 1944 after Hoeckner was killed in a takeoff accident. On 18 December, Steinmann succeeded in shooting down a RAF Mosquito for his 29th Abschuss.

In March 1945, Steinmann was transferred to III./EJG 2 and underwent conversion training to the Me 262 jet fighter. There he recorded four victories flying in the Turbinejäger, including two USAAF B-17 four-engine bombers.

Major Steinmann was finally awarded the Ritterkreuz on 28 March 1945 after achieving 44 Abschüsse, his final total. He served the last few weeks in JV 44 under the command of Generalleutnant Adolf Galland.

Wilhelm Steinmann survived the war having flown 234 missions. All but four of his 44 victories were achieved against the Western Allies. Note the name "Dixi" written in small white script under the cockpit. The subdued camouflage of this Bf 109 G-2 is rather interesting with an overall upper surface camouflage of RLM 74 gray with irregular patches of RLM 76 blue-gray.