In December 1939 two sites were chosen for two boom defence twin 6 pdr 10cwt guns, one at Dudley Point and one at West Point. This site began its wartime role in 1937 when a Naval Extended Defence Station was proposed to house detection instruments for use with submarine indicator loops at the boom net. In 1940 the station was erected here close to the Port War Signal Station. The location was extremely vulnerable however and it was moved after the 1942 Japanese raids. Only the concrete slabs remain and its later location remains a mystery. However the site was ideal for harbour defence and the plans for a twin 6 pounder battery here were revised. Unfortunately Darwin was sixth in priority and it was not until 1943 that work began. A July 1943 report on the forces available to meet an invasion included Dudley Point with a single Twin 6pdr 10cwt gun covering part of the boom. The Battery Observation Tower was constructed in conjunction with the battery here and was enclosed with corrugated iron cladding and camouflaged It was a popular lookout for visitors until conservation works and safety concerns forced its closure in 2007.