Tags: Military Structure.
Fort Ruger is a fort on the island of Oʻahu that served as the first military reservation in the Territory of Hawaii. Named after Civil War General Thomas H. Ruger and built in and around Diamond Head Crater the fort was established by the United States for the purpose of defending the harbor of its newly annexed territory. The fort was established in 1906 as Diamond Head Reservation and renamed Fort Ruger in 1909.