Fort Jackson is an historic masonry fort located some 40 miles (64 km) up river from the mouth of the Mississippi River in Plaquemines Parish, Louisiana. It was constructed as a coastal defense of New Orleans, between 1822 and 1832, and it was a battle site during the American Civil War. It is a National Historic Landmark. It was damaged by Hurricanes Katrina and Rita, and its condition is threatened. Following the engagement, Fort Jackson was used as a Union prison. It was here that the French champagne magnate Charles Heidsieck was held for seven months on charges of spying.