Each week American Artifacts takes viewers into archives, museums and historic sites around the country. At the outbreak of the Civil War in the spring of 1861, Washington, DC, was lightly defended and vulnerable to attack, with only one fort located 12 miles south of the city and the Confederate state of Virginia just across the Potomac River. By 1865, the nation’s capital arguably had become the most fortified city in the world, with about 70 armed forts and batteries encircling the city. We visited three of the surviving forts with Dale Floyd, author of a study on the Civil War Defenses of Washington for the National Park Service.