During the war of 1812 after much of Washington had been destroyed, the British army proceeded toward the Baltimore harbor, which was guarded by Fort McHenry. To block the ensuing army, American troops had sunk several ships to barricade the entry into the harbor. This forced the British to bombard Fort McHenry from a great distance. On the night of September 13, American prisoners on a British ship watched the fire in the night sky as the British army bombarded Fort McHenry. After many hours of continuous bombing, the British decided to leave, unable to destroy the fort.