Jagdgeschwader 300 employed the Wilde Sau tactic in single-engined fighters for the first time on the night of 3/4 July 1943, when 653 RAF aircraft attacked Cologne's industrial area on the east bank of the Rhine.

To avoid losses to friendly fire, anti-aircraft batteries were ordered to restrict the height of their flak barrage and the fighters operated above that ceiling.

Jagd-Division was initially far from a fully established Jagdgeschwader, the formation process was sped up with RAF Bomber Command deployment in July 1943 of Window; radar-jamming tin-foil strips which had rendered the Luftwaffe radar control system ineffective.

JG 300 and its sister units were the only interim counter measure, while Luftwaffe radar researchers strove to overcome this jamming.

Its first formal defensive operation on 27/28 July 1943 saw the unit claim four of the 17 bombers downed that night for one loss.

[5] The number of night accidents involving single-seat fighters caused by poor weather in the winter of 1943, led to unsustainable losses in pilots and aircraft.

By early 1944 the Nachtjagdgeschwaders has been equipped with the advanced and "window-proof" Lichtenstein SN-2 VHF airborne radar and JG 300 gradually evolved into a standard day fighter unit, flying operations against the USAAF 8th and 15th Air Forces over Western Europe as a part of Reichsverteidigung (Defense of the Reich).

[2][page needed] Night operations were still sometimes flown, as on the 24/25 March 1944, when I. and II./JG 300 claimed 7 RAF bombers for one loss.

[citation needed] In the summer of 1944 Sturmgruppe units were raised, equipped with heavily armoured and armed FW 190 fighters and charged with breaking up the massed ranks of USAAF daylight bombers.

(Sturm) Gruppe Jagdgeschwader 3, escorted by two Gruppen of Bf 109s from JG 300 led by Major Walther Dahl.

Dahl drove the attack to point-blank range behind the Liberators of the 492nd Bomb Group, which at the time was temporarily without fighter cover, before opening fire.

/JG 3 had nine fighters shot down and three more suffered damage and made crash landings; five pilots were killed.

[8] Major Alfred Lindenberger, (a forty-seven-year-old Prussian World War I ace with 12 victories) was posted to II.

Major Dahl was dismissed from his command of JG 300 by Hermann Göring on 30 November 1944, for refusal to launch what he considered a suicidal interception mission.

The Geschwader took heavy losses in late 1944, particularly on 17 December when 100 aircraft of JG 300 intercepted USAAF bombers, claiming 33 shot down but losing 43 of their own number.