FLAK

Firing from German anti-aircraft guns were known to the American and British airmen known as FLAK, short for FLugzeugAbwehrKanone.

The German army used different caliber FLAK ranging from grenades of 20 mm (light) to 128 mm (heavy). Probably there were many 20mm Flakvieling 38 placed along the Dutch coast. This was light flak. Most aircraft guns were placed around IJmuiden (Fortress IJmuiden) and around Hoek van Holland (Festung Hoek van Holland). These defense bastions were part of the Atlantic Wall.e Atlantikwall.

If multiple spotlights were directed on a plane, it would shine brightly in the night sky and so became a clear target for anti-aircraft guns.