Jagdgeschwader 300 (JG 300) was a Luftwaffe fighter-wing of World War II. JG 300 was formed on June 26, 1943 in Deelen as Stab/Versuchskommando Herrmann, from July 18, 1943 as Stab/JG Herrmann and finally renamed on August 20, 1943 to Stab/JG 300. Its first Geschwaderkommodore was Oberstleutnant Hajo Herrmann.
JG 300 had its origins in April 1943, when Major "Hajo" Herrmann, a decorated bomber pilot, advocated the use of single-seat day fighters as night fighters against the Royal Air Force (RAF) bomber offensive. He suggested that single seat fighters could operate in the bombers' general target area using the light of target indicators, massed searchlights and the fires on the ground to spot their targets. These operations were tested over Berlin during May and June 1943 and codenamed Wilde Sau.
Recruiting a group of experienced bomber pilots and former instructors with the requisite blind-flying experience, a test unit was set up on June 26, 1943 in Deelen as Stab/Versuchskommando Herrmann to test Herrmann's theory. Standard Fw 190-As and Bf 109-Gs were used, initially 'borrowed' from their parent day units, principally Jagdgeschwader 1 and Jagdgeschwader 11.