He then fought in defense of the Reich against the United States Army Air Forces (USAAF) heavy bombers.

On 2 April 1944, Remmer was killed in action near Graz when his parachute failed to open after he was shot down by USAAF fighters.

[1] Following flight training,[Note 1] he was transferred to the Ergänzungsstaffel (Training/Supplement Squadron) of Jagdgeschwader 27 (JG 27—27th Fighter Wing) on 2 January 1941.

[3] Following Operation Marita, the German invasion of Greece, the air elements of JG 27 briefly moved to Munich-Riem Airfield before they transferred to North Africa, arriving in Ayn al-Ġazāla between 18 and 22 April 1941.

[5] On 15 June, British forces launched Operation Battleaxe, an offensive to raise the Siege of Tobruk and re-capture eastern Cyrenaica.

The next day, the Royal Air Force (RAF) attacked the road from Fort Capuzzo to Al Adm and Tobruk.

[6][Note 2] On 26 August, he claimed his second aerial victory over a Hawker Hurricane north of Sidi Barrani[8] In late October, I. Gruppe was reequipped with the Messerschmitt Bf 109 F-4/trop.

[9] Following the reequipment, Remmer claimed a Vickers Wellington bomber shot down on 21 November east of Sidi Omar, his third aerial victory.

[10] He then claimed a Hurricane south of Al Adm on 27 November and a Bristol Blenheim bomber east of Ayn al-Ġazāla the following day.

[18] That day, Remmer and his wingman escorted a Messerschmitt Bf 110 fighter on an aerial reconnaissance mission when they encountered a single aircraft near Abu Dweis.

In aerial combat with about 20 Curtiss P-40 Warhawk fighters southeast of Fuka, pilots of I. Gruppe claimed four P-40s shot down including one by Remmer.

Tasked with patrolling the area of the Seine estuary up to Dieppe in the east and the Cotentin Peninsula in the west, the Gruppe faced the RAF during the Circus offensive as well as the first appearances of the United States Army Air Forces (USAAF) heavy bombers.

[28] On 13 May, 169 USAAF Boeing B-17 Flying Fortress bombers, escorted by fighter aircraft, attacked the Potez manufacturing sites at Albert and the Luftwaffe airfields near Saint-Omer.

[29] In early June 1943, I. Gruppe of JG 27 moved to the airfield at Marignane, present-day the Marseille Provence Airport.

At Marignane, I. Gruppe was subordinated to Jagdfliegerführer Südfrankreich (Fighter Leader Southern France) commanded by Oberst Friedrich Vollbracht and equipped with the Bf 109 G-4 and G-6.

Until their relocation to Münster-Handorf Airfield in late July, the Gruppe trained and prepared for action in defense of the Reich.

The aircraft were then equipped with the 20 mm MG 151/20 underwing gun pod to better effectively combat the USAAF heavy bombers.

That day, the USAAF VIII Bomber Command dispatched 330 B-17s from the 1st and 4th Bombardment Wing on a mission to Bochum, Gelsenkirchen, Recklinghausen and Bonn.

Over the next 45 minutes, I. Gruppe engaged the bombers, claiming five B-17s destroyed, including a B-17 shot down by Remmer south of Bonn.

[32] The Gruppe relocated from Münster-Handorf to an airfield at Fels am Wagram, located approximately 17 kilometers (11 miles) east-northeast of Krems an der Donau in Lower Austria, on 22 August.

[34] The Gruppe flew its first combat mission from Fels am Wagram on 1 October when the USAAF targeted the German aircraft industry.

As part of Operation Argument on 22 February, the USAAF Fifteenth Air Force targeted the Messerschmitt factories at Regensburg-Obertraubling and Prüfening.

In 20 minute aerial combat, Remmer claimed a B-24 and an escorting Lockheed P-38 Lightning fighter shot down southwest of Linz.

[46][47] According to Obermaier, Remmer was credited with 27 aerial victories, all of which claimed over the Western Allies in an unknown number of combat missions.