The Secret Military Defenses of Hawaii in 1941
It was such a long time ago now, Pearl Harbor, Dec. 1941. But back then, Hawaii was just a remote military outpost and Hawaii was, well, its own country, in many ways. Kind of like Guam and Puerto Rico are now. So remote was the outpost that it was "unthinkable" that anyone or thing would want to attack it. The Pacific Fleet had recently moved there from San Diego and many wondered why. Immediately after the PH attack, many in Congress and Senate sought to pull all military forces off the island than risk more devastation and return them to the mainland. The arguments were valid and strong and voting was close.
With that mindset, the US Army prepared secret defenses of the island, which shows just how brilliant the Japanese were in their careful attack preparations. Yamamoto had also planned to land a division of ground forces in the Haleiwa area, north shore. The original plan called for Japanese troops to occupy it, not just bomb it and the sink the USN. In the end, Yamamoto thought have a division of troops carried thousands of miles across the ocean would be too risky for it would slow down the whole convoy. Lucky us! For the only defenses there were two batteries of 155mm, one battery of 240mm and some spotlights! Yamamoto was also concerned about supply the Japanese force once they landed, as the island would have to be taken within a week's time. While the landing would have been unopposed, a mere seven miles away were the US 24th and 25th Divisions, on paper, it sounded like an imposing force, however, in reality, they were mostly "inexperienced" soldiers. They were also not well equipped.
Around Schofield Barracks and Wheeler AB were six AA companies from the 98th AA, all 24 guns. The Japanese aircraft attacked from the north, encountering zero AA defenses until they descended onto Schofield and PH. Hickham AB had only 2 AA companies for defenses, and those were actually south of the airbase! Along the southern coast from Ewa beach to Ahua Pt, were seven AA batteries (32 guns), Pearl City has four AA guns, as did Waipahu, Honolulu, Waikiki and Ft. Shafter. Diamond Head had eight AA guns. All total, Oahu had only 28 AA guns to defend against air attacks! Ford Island where most of the USN docked had no air defenses! Its only air defenses amounted to three F3A-3, one F4F-3 and three SBD-2 dive bombers.