It appeared to military planners of the 1930s that the major threat to Pearl Harbor would come from the sea and that the presence of a strong fortification to secure the harbor entrance was crucial. Fort Kamehameha stands near Holokahiki Point to the south-east of the entrance and here heavy artillery was installed capable of inflicting damage on the heaviest of warships. Like the great guns facing seawards at Singapore, they proved to be irrelevant. 55th Coast Artillery was based at the Fort and was roused into action on 7 December 1941 by Japanese aircraft attacking Hickam Field.
You can learn more about Fort Kamehameha in the following Osprey book: