Fort Stevens was an American military installation that guarded the mouth of the Columbia River. It was built near the end of the American Civil War and was an active military reservation from 1863–1947. On June 21, 1942, a Japanese submarine with a crew of 97, and transporting a Yokosuka seaplane, entered US coastal waters following fishing boats to avoid minefields. The submarine later surfaced and opened fire on Fort Stevens with a deck gun. American Army Air Corps planes on a training mission spotted the submarine but the submarine submerged undamaged. Read more here and here. Click here to download the CoastView app and explore Fort Stevens and the mouth of the Columbia River.