During the Civil War, Union soldiers brought their cannons to this site above the mouth of the Columbia to guard the entrance to the mighty river. The increasingly modern artillery remained on sentry duty at Fort Stevens until shortly after World War II. A small museum tells of those many years of being on alert, with a special emphasis on the fort's one moment of action-the night of June 21, 1942, when a Japanese submarine fired 17 rounds onto the fort's grounds, causing tremendous excitement but no harm. Visitors may wander through the old concrete bunkers on the bluff.