In September 1814, Francis Scott Key composed a poem, “Defence of Fort M‘Henry,” after witnessing U.S. forces defend Fort McHenry, the fortress guarding Baltimore Harbor, against a fierce British bombardment. He combined it with the tune of an 18th-century British song, “Anacreon in Heaven.” Key’s creation would forever after would be known by another name, of course, “The Star-Spangled Banner.” Popular from the start, it was officially decreed to be the national anthem 117 years later.