Final answer:
The event that inspired "The Star-Spangled Banner" was the British bombardment of Fort McHenry during the War of 1812. Francis Scott Key wrote a poem about the flag that continued to wave over the fort, and this poem later became the U.S. national anthem.
Step-by-step explanation:
The event that inspired "The Star-Spangled Banner" was the British bombardment of Baltimore's Fort McHenry during the War of 1812. After the British failed to conquer the fort, Francis Scott Key was inspired by the sight of the American flag still waving triumphantly. He wrote the poem "In Defense of Fort McHenry," which later became the U.S. national anthem. The flag's large size, measuring 30 by 42 feet and being 90 feet above the ground, contributed to its visibility from miles away.