Fort Stevens was established during the Civil War to defend the Columbia River from naval invasion. Occupying the northwestmost corner of Oregon, the fort`s position has been of supreme military importance, at least to the residents of that part of the country. To a Congress engaged in an expensive civil war, it was not nearly as clear that the fort was needed, and construction was delayed until 1863 so that the war was nearly over when the construction team declared the fort to be operational in Apri l865.
The fort remained important during the period of tensions with Britain in subsequent decades, including the period of the Pig War in the San Juan Islands. Its only episode that approached combat was when it was attacked by a Japanese submarine on June 21, 1942. It was fired upon but did not return fire.
The US Army abandoned Fort Stevens in 1947. Much of the land is now Fort Stevens State Park. The area of greatest military importance has been preserved to some extent and military reenactments take place regularly.