In this period the developing night fighter arm was engaged in protecting Germany and the Ruhr. The aircraft operated mainly over Germany and the Low Countries. Airfields developed along the Kannhuber line, Schleswig, Stade, Luneburg, Wittmundthaffen, Oldenberg, Vechta, Leeuwarden, Twente, Deelen, St Trond and Venlo among others. It's a line running from the NE Franco-Belgian border in a north easterly direction, up towards Denmark, facing the North Sea, where the RAF bombers would come from.
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Steve