To protect the entry to the important port city of Trieste, the German Navy had at the end of 1943 four Italian 90 mm. guns located strategically south of the city. The guns have a range of 12 km. and could be used both against targets on the water and in the air. The guns were set in open ring positions cast in concrete.
Istria had been Italian since 1920 and after Italy in September 1943 retired from the war, the Germans took over the defense.
The waters around Istria were important to the Germans, partly because of the transport of supplies, troops and resources from the many small port citys along the coast to Trieste.
The remains of the gun battery are now scattered around the fields of the Debeli Rtič nature reserve.