Answer: Which fort was completed before the American Civil War to defend San Francisco Bay against hostile warships?
Answer: Fort Point
Fort Point is located at the southern side of the Golden Gate at the entrance to San Francisco Bay. This fort was completed just before the American Civil War, to defend San Francisco Bay against hostile warships. The fort is now protected as Fort Point National Historic Site, a United States National Historic Site administered by the National Park Service as a unit of the Golden Gate National Recreation Area.