Freya was an early warning radar deployed by Germany during World War II; it was named after the Norse goddess Freyja.

Because of its complex design, only eight Freya stations were operational when the war started, leaving large gaps between the covered areas.

Freya was first successfully used on December 18, 1939 when two stations detected an approaching daytime raid on Wilhelmshaven by 22 RAF Vickers Wellington bombers at a range of 113 km and guided fighter planes toward them via radio.

[1] Only half of the Wellingtons returned to Britain undamaged, but the German fighters only reached the bombers after they had made their bombing run on ships in harbour.

When Britain started its bombing raids, Hermann Göring ordered Colonel (later General) Josef Kammhuber to install an efficient air defence.

In the later course of the war, Freya devices turned out to be vulnerable to chaff, and other countermeasures, which still allowed then to be used for early warning, but no longer for guiding fighter planes.

Sneum's deed is also mentioned in R. V. Jones's Most Secret War as a 'most gallant exploit' and is one of the featured stories in Courage & Defiance by Deborah Hopkinson.

By using nine aeroplanes, a 200-mile (320 km) gap could be knocked into the German's radar coverage, while further jammers were carried in the bomber stream to counter the inland Freya network.