But Baltimore was defended by Fort McHenry — a star-shaped fort perfectly situated on the Baltimore Harbor. On the morning of September 13, 1814, the British navy attacked the fort for 25 hours.

A 3.5-inch-diameter 32-pounder was the most favored size—and the kind fired against Fort McHenry on September 13 and 14, 1814. It carried seven pounds of incendiary mixture. Both the American ...