During the Civil War, nine magazines stood within the fort's bastions and fronts, all located at parade ground level. They were lined with wood so a soldier's gun or belt buckle would not strike the granite walls and create a spark that could ignite volatile black powder. This large magazine, built for storing bulk ordnance supplies, was part of an 1869 modernization plan. Its isolated location, heavy construction, and surrounding wall reflected further efforts to protect the garrison from accidental explosions. Additional magazines were built at the same time on top of the coverface near the long-range artillery.