The Star-Spangled Banner Flag 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. Seeing the flag during the battle inspired Francis Scott Key to write the poem "Defence of Fort McHenry", which, retitled with the flag's name of the closing lines of the first stanza and set to the tune "Anacreon in Heav'n," would later become the national anthem of the United States.