Fort Simcoe, on the Yakima Indian Reservation, was the station of the Ninth Regiment of the U.S. Infantry between 1856 and 1859. Once the wars between the Indian nations and white residents ended, the fort was used as an Indian agency and school. A number of the original buildings still stand, and artifacts from the military post and Indian materials are exhibited.

     Fort Casey and Fort Flagler, located across from each other at the northern end of Puget Sound, protected the Bremerton Navy Yard and Puget Sound from hostile ships. Fort Worden, acquired by the Commission in 1964, completed the "triangle of fire." Fort Ward, acquired in 1921, is located on Rich Passage near the Bremerton Navy Yard. This fort provided a second line of defense for the yard should the more northerly forts fail to stop the enemy. Fort Casey has four interesting guns used in coastal defense fortifications. Only a few such guns remain on public display. The "triangle of fire" forts became outdated as technology changed. However, these forts were used for coastal protection through World War ll. 

     Two forts near the mouth of the Columbia River were also acquired at this time. Though the dangerous bar of the Columbia forbids an easy passage, and thus provides some protection from invading ships, the military planners of the 19th century thought this natural barrier insufficient. Fort Columbia and Fort Canby were both added to protect the west coast from any enemy who might defeat the bar and sail upriver to Portland and the interior. Fort Canby is the older of the two, built in 1875. Guns had been installed at the site as early as 1862. Fort Columbia, a little up river from Fort Canby, was built around the turn of the century. Though it served through World War II, its guns never fired at enemy ships or troops.