On 18 July 1941, Fiegel was killed in action flying a Focke-Wulf Fw 200 during the Atlantic War in an attack on convoy OB 346.

That year, he also participated in the UCI Track Cycling World Championships held in Zürich, Switzerland where he lost in the knockout stage to the Austrian August Schaffer.

[3] Fliegel joined the military service in 1934 and transferred from the infantry of the Reichsheer (Army) to the newly emerging Luftwaffe (Air Force) of Nazi Germany a year later.

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

Fliegel flew combat missions over Poland and received the Iron Cross 2nd Class (Eisernes Kreuz 2.

[1] On 6 February 1941, U-37 under the command of Kapitänleutnant (Captain Lieutenant) Nicolai Clausen, spotted convoy HG 53, 19 merchant ships escorted by HMS Velox and Deptford, heading for Liverpool.

[6][7][8] This achievement earned him his first mention in the Wehrmachtbericht, an information bulletin and element of Nazi propaganda issued by the headquarters of the Wehrmacht.

[9] On 18 July 1941, Fliegel and his crew—copilot Leutnant (Second Lieutenant) Wolf-Dietrich Kadelke, first radio operator Oberfeldwebel (Staff Sergeant) Johannes Rottke, second radio operator Gefreiter (Airman) Karl Becker, flight engineer Unteroffizier (Sergeant) Johann Kothe and air gunner Unteroffizier Karl Meurer—were reported missing in action over the Atlantic in the vicinity northwest of Ireland.