Francis Scott Key wrote the poem that became the lyrics of the U.S. national anthem after seeing Fort McHenry’s flag in 1814.
Key wrote “Defence of Fort M'Henry” after witnessing the American flag flying over Fort McHenry in Baltimore Harbor on the morning of September 14, 1814. The fort had endured a British bombardment during the War of 1812 and had not fallen.
The poem was later set to the tune “To Anacreon in Heaven,” an English song associated with John Stafford Smith. In 1931, the song became the official national anthem of the United States and was renamed “The Star-Spangled Banner.”
The flag that inspired Key was the large garrison flag made by Baltimore flagmaker Mary Pickersgill and her helpers. It is distinct from the later anthem itself: the flag is a physical artifact, while Key’s poem supplied the words.