Natural Bridge Battlefield Historic State Park in Florida lies between Tallahassee and St. Marks at a natural bridge where the St. Marks River flows underground. It preserves the site of the Battle of Natural Bridge, fought there on March 6, 1865, late in the American Civil War. The crossing gave the landscape both its name and its strategic importance, and the surviving battlefield reflects how the terrain, river, and bridge shaped events. Now both a historic battlefield and a state park, the site includes protected land acquired by the Civil War Trust, now part of the American Battlefield Trust, and its partners.