It was on this day in 1814 that an American lawyer and poet named Francis Scott Key wrote what was to become his most famous poem, “Defence of Fort McHenry,” while on board a British Navy ship in Chesapeake Bay. Key had been negotiating with the British for the release of a prisoner they had taken in a raid on Washington, but because he had heard about the Navy’s plans for attacking Baltimore, he was not released until after the battle. That was how he came to witness the bombardment of Fort McHenry from the deck of H.M.S. Tonnant on the night of September 13. When the sun rose the following morning, and Key saw the stars and stripes flying over Fort McHenry, the sight inspired him to write a poem. Soon afterward, Key’s words were set to the melody of a popular song by English composer John Stafford Smith. “The Star-Spangled Banner” became the national anthem of the United States on March 3, 1931.