In late 1941, he served with Jagdgeschwader 5 (JG 5—5th Fighter Wing) which was moved near the Arctic Ocean in the northern sector of the Eastern Front.

Dörr was born on 10 February 1913 in Mannheim, at the time in the Grand Duchy of Baden of the German Empire.

In addition to its training role, its mission was to provide air defense for Jutland's western coast.

Approximately 25 kilometers (16 miles) east of Pechenga, the flight encountered eight Hawker Hurricane and six Curtiss P-40 Kittyhawk fighters flying at low altitude.

According to Soviet records, only one Hurricane was lost, its pilot Senior Lieutenant Lewtschuk from 197 IAP (197th Fighter Aviation Regiment—Istrebitelny Aviatsionny Polk) bailed out.

[5] On 15 May on a fighter escort mission to Murmansk, Dörr claimed his second aerial victory when he shot down a Hurricane.

In the resulting aerial combat, Dörr claimed one of the fighters shot down, which he had identified as a Curtiss P-40 Warhawk.

[7][8] On 12 July 1943, Dörr lost his Messerschmitt Bf 109 G-2 (Werknummer 13600—factory number) over sea, officially due to engine trouble.

[9] Mombeek speculates that in fact the aircraft was lost in a mid-air collision with another Bf 109 G-2 piloted by Unteroffizier Richard Steinbach.

[10] Shortly after, Dörr was awarded the Iron Cross 2nd Class (Eisernes Kreuz zweiter Klasse) and the Iron Cross 1st Class (Eisernes Kreuz erster Klasse) following his eighth victory claimed on 23 January 1943.

[12] JG 5 flew multiple missions from Pechenga and Kirkenes in protection of a German convoy on 14 September.

At 17:03, a Rotte of Bf 109 G-2s sighted and reported an enemy formation consisting of Douglas A-20 Havoc, also known as Boston bombers, Ilyushin Il-2 ground attack aircraft, as well as Bell P-39 Airacobra and Hurricane fighters.

[13] On 25 November, following ten days of relative quiet, the Soviet Air Forces conducted a coordinated attack on Titovka, and the airfields Høybuktmoen at Kirkenes and Luostari near Pechenga.

[15] That day, Dörr claimed a P-40 and an Il-2 ground attack aircraft, taking his total to 31 aerial victories.

This time the Germans reported combat with approximately 100 Soviet aircraft and claimed 40 aerial victories, among them five by Dörr.

[20] On 1 August, Geschwaderkommodore (Wing Commander) of JG 5, Oberstleutnant Scholz was given the position of Jagdfliegerführer Norwegen.

In parallel, further Soviet aircraft, including a number of Boston bombers, attacked the harbor at Kirkenes.

Gebirgs-Armeekorps was on the retreat and threatened by encirclement from Soviet forces that breached the German defenses south of the Petsamo (Pechenga) airfield during the Petsamo–Kirkenes Offensive.

Neither Dörr nor his Geschwaderkommodore Ehrler knew the exact location of the battleship and were told she was based near Tromsø.

[29] The command and control center at Bardufoss was informed shortly before 08:00 that three Lancasters had been sighted at 07:39 in the vicinity of Mosjøen heading east.

The reason for this delay in communication was that the message had been routed from Mosjøen to Fauske and then to the Luftwaffe headquarters at Narvik.

The communication officer in charge, Leutnant Leo Beniers, immediately forwarded this information to Tromsø.

At 08:18 the Luftwaffe fighter control center was informed which issued an air alarm for the area of Bodø.

At 08:34 further four Lancasters were reported but plotted in the wrong Planquadrat (PQ—grid reference) of the Luftwaffe grid map (Jägermeldenetz).

Ehrler, who had planned to fly to Alta, entered his command post at 08:50, unaware of the unfolding events.

In parallel, Dörr who was alarmed by the fighters taking off, arrived at the command post and took charge of the Kommandostaffel.

[33][34] The naval officers on board Tirpitz were notified Erhler was airborne before the British began their attack at 09:38.

[36] According to Forsgren, Dörr may have intercepted and shot down an unidentified aircraft 20 kilometers (12 miles) northeast of Bardufoss that day.