Historical Stuff:

The true historical JG 300 was a fighter group which was stationed at Bonn-Hangelar during the latter part of World War II. Unlike most JG's, JG 300 was a night and day fighter group.  Formed as a wild sau (sow) unit over the summer months of 1943, JG 300 was under the command of Major Kurt Kettner. The Wild Sau units came into their own during the long summer nights when Bomber Command returned to Berlin.  JG 300 claimed 56 bombers on the night of August 24th, operating in good visibility above a flak-free zone; 47 were claimed on the night of September 1st and an additional 26 on the night of September 4th. The pace continued throughout the autumn as RAF Bomber Command sought targets at Mannheim, Hannover and Kassel.  However, with the onset of winter, losses rose alarmingly and, although some Wild Sau elements of JG 300 continued night operations, most were retrained for combat operations against day bombers of the 8th USAAF.

More information can be obtained from the OFFICIAL JG 300 website