Battery Harlow (Honolulu, Hawaii)

 military, gun, fortification, artillery battery

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Eight 12" mortars M1890M1 were mounted here from 1910 to 1943.

Part of Ft. Ruger Military Reservation.

Battery Harlow was the first structure built at Fort Ruger, starting in April 1907 and finishing by March 1910. The Battery is outside the crater on the north side and is a bunker style battery designed to fire over and across Diamond Head Crater out to sea. Battery Harlow had a 360 degree field of fire though, and had the range and elevation to fire over the mountains to the north into Kaneohe Bay.
The Battery is designed in the shape of a capital letter E with a pair of 4 mortar gun pits between the arms of the E. The E itself is a solid building with thick concrete walls and covered with many feet of soil. There are fire control facilities, offices, store rooms, powder and shell rooms, and an underground power room. The Battery received power from a 25kW generator run by a 50 HP gasoline engine. There are lantern alcoves throughout the structure to be used in the event of a power failure. The center leg has a mechanical communication system that was used to signal firing information to the gun pit crews on either side. There is a pair of "built in" concrete megaphones in the wall, and two sets of mechanically cranked numbers that the Fire Control officers could use to signal the Elevation and Azimuth settings.