The Freya radar , with a range of 100 miles , was used to detect an incoming bombers at long - distance .
The Freya radar that Harald investigates was part of the Kammhuber Line , the German night air defense system along the North Sea .
The Freya part , with a range of 100 miles , was used to detect an incoming bombers at long - distance .
The Freya radar that Harald investigates was part of the Kammhuber Line , the German night air defense system along the North Sea .