The Star-Spangled Banner, or the Great Garrison Flag, was the garrison flag that flew over Fort McHenry in Baltimore Harbor during the naval portion of the Battle of Baltimore during the War of 1812. It is on exhibit at the National Museum of American History, Smithsonian Institution. Seeing the flag flying over Fort McHenry on the morning of September 14, 1814, after the battle ended, Francis Scott Key was inspired to write the poem "Defence of Fort M'Henry". These words were written by Key and set to the tune of "To Anacreon in Heaven" by John Stafford Smith, a popular song at the time. It was not until 1931 that the song became the national anthem of the United States.