Artillery
The principal danger to the military installations on Oahu was thought to be a seaborn attack by capital ships followed by invasion. The Army had field artillery available as a mobile opposition to landings and the 55th Coast Artillery at Fort Kamehameha had both heavy guns and mobile guns to fire on shipping.
See also: 55th Coast Artillery; Fort Kamehameha; Hawaiian Army Command; Oahu.
You can find out more about artillery in the following Osprey books:
CAMPAIGN 62 Pearl Harbor 1941; CAMPAIGN 30 Midway 1942; MEN-AT-ARMS 342 US Army in WWII (1) The Pacific; ELITE 59 US Marine Corps 1941-45