[1] On 15 September 1941, he was posted to the Jagdfliegerschule 5 (JFS 5—5th fighter pilot school), stationed at the Le Havre – Octeville airfield in France.

Staffel (11th squadron) of Jagdgeschwader 51 "Mölders" (JG 51—51st Fighter Wing) operating on the Eastern Front.

[5] According to Obermaier, Marquardt claimed his first aerial victory on 2 October, shooting down an Ilyushin Il-2 ground-attack aircraft.

[6] Following the German retreat, the Gruppe moved to an airfield at Lida, which is 150 kilometers (93 miles) west of Minsk, on 3 July.

Gruppe retreated to an airfield at Tilsit, present-day Sovetsk located on the south bank of the Neman River.

[3] Following a brief period of little combat in central Poland, Marquardt became an "ace-in-a-day" on 7 October, claiming two Il-2 ground-attack aircraft and a Douglas A-20 Havoc bomber, also known as Boston, on the first mission of the day.

[13] On a transfer flight of new Focke-Wulf Fw 190 D-9 to his unit, he was credited with four aerial victories over Yakovlev Yak-3 on 25 April 1945.

Due to lack of spare parts, the damage was not reparable and the aircraft was blown up to prevent it from falling to the enemy.

[15] On 1 May 1945 Marquardt became Jagdgeschwader 51's last casualty of the war when he was shot down by Royal Air Force Spitfires north of Berlin.

Marquardt was initially reported as killed in action but he had bailed out injured and was taken to a hospital in Schwerin, where he was taken prisoner of war shortly after.

[14] Following World War II, Marquardt served in the newly established German Air Force of West Germany with the rank of Leutnant (Second Lieutenant) on 16 August 1956.