Eder joined the Luftwaffe as Fahnenjunker at the age of 17 in 1938. In the beginning of April 1939 Eder enrolled in the Luftkriegsschule 2 (air war school) at Berlin-Gatow. His first combat appointment was to 1 Staffel, Jagdgeschwader 51 (JG 51—51st Fighter Wing) on 1 September 1940. He flew all through the Battle of Britain but did not claim any victories.
In May 1941 he joined 4./JG 51 and claimed his first aircraft, a Spitfire, on 7 May. Eder then flew with JG 51 in the opening months of the campaign on the Eastern Front, destroying two Russian aircraft on 22 June. However, on 24 July he was shot down and slightly wounded. On 22 August, after 10 victories, Eder's fighter collided with a Junkers Ju 52 on the ground at Ponjatowska. Eder suffered a skull fracture.
After recovery, Eder served as a flight instructor with Jagdfliegerschule 2 (fighter pilot school) at Zerbst from November 1941 to November 1942.
In November 1942 Eder was sent to 7./Jagdgeschwader 2 "Richthofen" (JG 2—2nd Fighter Wing), named after the after World War I fighter ace Manfred von Richthofen, in France, and participated in the battle against the American Eighth Air Force day bombing offensive. With Hauptmann Egon Mayer of III./JG 2 "Richthofen", Eder developed the head-on attack strategy to combat the formations of Boeing B-17s and Consolidated B-24s. The concept was based on a Kette (chain), three aircraft flying in a "V" formation, attacking from ahead and to the left. When in range, the attackers opened fire with a deflection burst, aiming in front of the enemy aircraft. Following the attack, the pilots would pull up sharply to the left or right. This gave the attacking fighters the best chance of avoiding the massed firepower of the bombers' guns.
In February 1943 Eder became Staffelkapitän (squadron leader) of 12./JG 2 "Richthofen". On 28 March after downing a B-17, he was wounded when his Messerschmitt Bf 109 G-4 somersaulted on landing at Beaumont-le-Roger. Eder destroyed his 20th aircraft on 29 May 1943. On 5 September 1943, Eder was transferred to 5./JG 2. On 5 November, Eder was again forced to bail out of his Bf 109 and was again injured.
In March 1944 Oberleutnant Eder was transferred to 6./Jagdgeschwader 1 "Udet" (JG 1—1st Fighter Wing), named after the after World War I fighter ace Ernst Udet, in Northern Germany. He bailed out of his Focke-Wulf Fw 190 A-7 during combat with a P-47 "Thunderbolt" over Göttingen on 19 April. On 8 May, he claimed a B-24 but made an emergency landing at Vechta.
By the end of May he had a total of 49 victories. As Gruppenkommandeur II./JG 1 "Udet" he fought in the aerial battles over Normandy during the Allied invasion, and on 21 June 1944 recorded his 50th victory. On 24 June Eder received the Ritterkreuz.
On 11 August 1944 Eder took command of 6 Staffel, Jagdgeschwader 26 (JG 26—26th Fighter Wing). Attacking Allied armour near Dreux on 17 August Eder shot down a Spitfire at low level; it crashed between two M4 Sherman tanks, destroying them. Shortly after that he shot down another Spitfire, which crashed on another tank, setting it on fire.
On 4 September Hauptmann Eder became Gruppenkommandeur II./JG 26, after the unit's Gruppenkommandeur Hauptmann Emil Lang was killed in action against United States Army Air Forces (USAAF) Thunderbolts over St Trond. In September Hauptmann Eder was transferred to Erprobungskommando 262 and appointed Staffelkapitän, 1./Kommando Nowotny. On 19 November, following the redesignation of the unit to Jagdgeschwader 7 (JG 7—7th Fighter Wing), he commanded 9 Staffel, flying the Messerschmitt Me 262 in combat.
During the Ardennes offensive, Eder claimed 40 P-47s destroyed on the ground. He was awarded the Oak Leaves on 25 November 1944 for some 60 victories. On 22 January he was shot down near Parchim by P-51s while trying to land. He broke both legs and spent the rest of the war in hospital at Wismar and Bad Wiessee, where he was captured by the US Army.
Georg-Peter Eder flew 572 combat missions of which 150 were with the Messerschmitt Me 262. On the Eastern Front he scored 10 victories and on the Western Front 68, of which no less than 36 were four-engined bombers. With the Me 262 he scored at least 12 victories, at least one sources indicate that this number could be as high or even higher than 24 kills. He was the leading scorer against the four-engined bombers, and leading air ace against the USAAF, claiming some 56 US flown aircraft. Eder himself was shot down 17 times, bailing out 9 times, and was wounded 14 times.Iron Cross (1939) 1st Class (11 July 1941)
Ehrenpokal der Luftwaffe (16 June 1943)
German Cross in Gold on 31 August 1943 as Oberleutnant in the 12./JG 2
Knight's Cross of the Iron Cross with Oak Leaves
Knight's Cross on 24 June 1944 as Oberleutnant and Staffelkapitän of the 6./JG 1
663rd Oak Leaves on 25 November 1944 as Hauptmann and Staffelkapitän of the 6./JG 1